Nearly everyone will encounter cancer at some time in their lives, either through a personal diagnosis or the diagnosis of a relative or friend. Cancer is a common disease, with about 1.4 million new cases diagnosed each year in the United States alone. In fact, cancer has recently overtaken cardiovascular disease as the leading cause of death for Americans under the age of eighty-five, and it accounts for twice as many deaths as cardiovascular disease in those under sixty-five. Over a half million Americans die of cancer each year. This figure corresponds to more than 1,500 cancer deaths each day, or approximately 1 death per minute. Figure 1 shows the five leading sites of cancer incidence and their corresponding death rates in men and women.
Despite these numbers, there is reason for optimism. Even with increases in the American population, the rate of new cancer cases and deaths for all cancers combined dropped for the first time since record keeping began in the 1930s. Death rates from cancer have decreased each year from 1993 to 2002, the most recent year for which full data is available. Advances in prevention, early detection, and treatment have helped reduce death from cancer. More than 10 million people alive today with a history of cancer can attest to recent successes.
More immediate progress against cancer can be made in the areas of prevention and early detection. To achieve these goals, we must recognize that risks can be identified and reduced; tests can detect cancer in its earliest, most treatable stages; and many cancers can be prevented altogether by modifying our lifestyles.
Risk Factors
Risk factors are personal characteristics or events that may affect that person’s chance of developing a disease. Lifestyle, environment, and genetic makeup, alone or in combination, help determine cancer risk.
When thinking about cancer, it is sometimes useful to think of a risk factor as something that can cause insults, or “hits,” to the genetic structure of a normal cell. These hits cause normal cells to change to cancer cells by interacting with and altering a gene’s normal DNA and protein products. Cancer is an accumulation of these alterations, or mutations, that result from multiple events acting together over many years or decades. It is not a one-step, one-hit process.
Certain risk factors have been identified as causing hits that start a normal cell’s journey toward becoming a cancer cell. These risk factors hits include tobacco, X-rays, sunlight, industrial chemicals, some types of hormones and drugs, and certain viruses. Other hits promote the cell’s continued progression to cancer; alcohol and high-fat diets are associated with these hits. It may take several promoting hits to damage a cell beyond repair and mutate its DNA. As hits and mutations accumulate, the cell starts to grow uncontrollably, eventually becoming a cancer cell.
On the positive side, the human body does a remarkable job of protecting itself from cancer. Our cells are exposed to potential cancer-causing compounds (carcinogens) every minute of every day. Many of these compounds are by-products of normal body metabolism. The body has several lines of defense against these carcinogens, including mechanisms to protect DNA and to repair any DNA damage that occurs. Additionally, the body can alter the cell’s environment to make it more difficult for an already cancerous cell to grow in an uncontrolled fashion.
Risk factors can be classified as modifiable or nonmodifiable. We can do nothing about nonmodifiable risk factors, such as our gender, our race, our genes, and the hormones that are naturally produced by our bodies. But modifiable risk factors are risk factors that we can choose to change.
Nonmodifiable Risk Factors
Gender, Ethnicity, and Race Some of the gender differences for cancer are obvious. For example, the risk of breast cancer is approximately 100 times higher in women than in men. However, men are not entirely immune from this disease: Estimates suggest that more than 2,000 men in the United States will develop breast cancer in 2007. Similarly, race and ethnicity can have a significant impact on cancer risk. African-American men, for instance, are more likely to develop prostate cancer and often develop this cancer at an earlier age than men of other races. Individuals of Ashkenazic-Jewish descent have higher rates of mutations in breast cancer susceptibility genes such as BRCA1 and BRCA2. Many researchers are trying to improve our understanding of cancer risks in different populations so that prevention efforts can be tailored to meet these needs.
Heredity When the same types of cancer appear in a family for generation after generation, a genetic alteration (inherited from the father or the mother) may be the first damaging hit to the DNA that begins the cell’s change to cancer. Usually, other hits are required to sustain the cell’s progression to a tumor. Approximately 10 percent of all cancers result from hereditary predisposition. Most cancers are not hereditary in nature and result from a complex interaction of genes, environment, and lifestyle.
Hormones Produced by the Body One of the most important risk factors for developing breast cancer is a woman’s lifelong exposure to naturally occurring hormones. The longer a woman produces hormones, the more likely she is to develop breast cancer. Factors such as early menstruation (before age twelve) and late menopause (after age fifty-five) contribute to prolonged hormone exposure. The number of ovulatory cycles in a woman’s lifetime can also affect her risk of cancer. Women who have an increased number of uninterrupted ovulations have been shown to be more likely to develop ovarian cancer. This phenomenon may explain why events that interrupt ovulatory cycles, such as pregnancy, breast-feeding, and oral contraceptive use, are associated with a decreased risk of ovarian cancer.
Modifiable Risk Factors
Tobacco It is estimated that there are approximately 45 million current smokers and more than 46 million former smokers in the United States. All of these people are at increased risk for developing cancer. Tobacco use is the single most preventable cause of death in the United States. Cigarette smoking is directly responsible for at least 30 percent of all cancer deaths each year. Smoking also causes chronic lung disease, heart disease, stroke, and vascular disease.
More than 3,000 chemicals are present in tobacco smoke, including at least 60 known carcinogens. Some of these chemicals become carcinogenic only after they are activated by specific enzymes (proteins that control chemical reactions) found in many tissues in the body. These activated compounds can then mutate DNA and interfere with the normal growth of cells. Tobacco also contains nicotine, a chemical that causes physical addiction to smoking. During smoking, nicotine is absorbed quickly into the bloodstream and travels to the brain, causing the addictive effect.
Since the release in 1964 of the first surgeon general’s report on smoking and health, the scientific knowledge about the health consequences of tobacco use has greatly increased. It is now well documented that cancers of the lung, larynx, esophagus, mouth, and bladder are caused by smoking. Cigarette smoking is the most important risk factor for lung cancer, accounting for 68 to 78 percent of lung cancer deaths among females and 88 to 91 percent of lung cancer deaths among males. Additionally, smoking is known to contribute to cancer of the colon, stomach, cervix, pancreas, and kidneys.
Many people are under the impression that cigars and smokeless tobacco are safer alternatives to cigarettes. Considerable evidence shows that smokeless tobacco and cigars also have deadly consequences, including lung, larynx, esophageal, and oral cancers. Smokeless tobacco—chewing tobacco and dipping snuff—contains at least twenty-eight carcinogens. Habitual use of these products threatens the lives of several million Americans.
Children, too, are not spared addiction to tobacco. About 3 million adolescents report smoking at least once in the last month; 1.1 million report daily smoking. Nearly 4,000 young people begin smoking each day, and over 6 million people who decided to begin smoking as children will die early, preventable deaths. Clove cigarettes and flavored cigarettes are ideal “training cigarettes” for people in this age group; however, rather than being safer alternatives to regular cigarettes, these products are often unfiltered and have the same or greater health risks.
The risk of developing lung cancer, as well as other smoking-associated diseases, depends on an individual’s total lifetime exposure to cigarette smoke. Such exposure is measured by the number of cigarettes a person smokes each day, the age at which smoking began, and the number of years a person has smoked. For example, in those who smoke forty or more cigarettes a day (two or more packs), the risk of death from lung cancer is more than twenty times the risk in nonsmokers.
The harmful effects of smoking do not end with the smoker. Each year, exposure to secondhand smoke, also known as environmental tobacco smoke (ETS), causes an estimated 3,400 nonsmoking Americans to die of lung cancer. ETS has also been significantly linked with nasal sinus cancer in nonsmoking adults. The surgeon general has recently issued a report that states that there is no safe level of secondhand smoke.
Quitting smoking is a critical step toward improving health. Methods and resources that can aid in quitting can be found in “How Can You Reduce Cancer Risk?” in this post.
Diet and Nutrition Scientific studies suggest that about 30 percent of all cancer deaths are associated with poor dietary and nutrition practices. Specific risk factors include certain types of foods; methods of cooking, processing, and storage; and excessive caloric intake of food.
Substantial evidence shows that fats and alcohol are two dietary components that, when used imprudently, can increase cancer risk. Excessive dietary fats appear to play a role in the development of cancers at multiple different sites, including the breast, pancreas, endometrium (uterus), esophagus, and colon. Although saturated fats (derived mainly from animal sources) were considered the primary culprit in the past, both saturated fats and unsaturated fats have been associated with increased cancer incidence. Similarly, overuse of alcohol has been shown to contribute to breast, colorectal, head and neck, esophagus, and liver cancers. Risk increases with the amount of alcohol consumed and may start to rise with as few as two drinks per day. Many of the by-products of alcohol are recognized carcinogens.
Just as foods are a source for potentially dangerous carcinogens, so diet plays a role in protecting us from cancer. Populations that consume large amounts of plant-derived foods have decreased incidence of certain types of cancers, including those of the esophagus, mouth, stomach, colon, rectum, lung, and prostate. Fiber, fruit, and vegetable intake have been studied to determine their effects on colon cancer risk. Clinical trials that emphasized intake of these foods did not show a decreased rate of recurrence for colon polyps, which are considered precursor lesions for colon cancer. However, these results may be due to following the special diets for too short a time to have an effect. Intake of fiber, fruits, and vegetables is still strongly encouraged due to the other health benefits from these foods. Some of the main results from these studies are summarized in Table 1.
Table 1. Selected Large Dietary Intervention Trials for Cancer Prevention9% reduction in breast cancer risk (nonsignificant)Participants did not achieve the low-fat goal; may not have had long enough follow-up period to detect a difference.8% reduction in colon cancer risk (nonsignificant); mild reduction in colon polypsParticipants did not achieve the low-fat goal; may not have had long enough follow-up period to detect a difference.Women’s Intervention Nutrition Study24% reduction in risk of breast cancer recurrenceMay be useful for women with tumors that are negative for estrogen receptors.No difference in risk of recurrence; trend toward reduction of risk in menMay not have had a long enough follow-up period to detect a difference.24% reduction in risk of breast cancer recurrence4% reduction with dietary changes (nonsignificant); trend toward reduction in menMay not have had a long enough follow-up period to detect a difference.Levels of micronutrients may also play a role in determining cancer risk. People with higher levels of the micronutrient selenium have been found to have fewer deaths from lung, colorectal, and prostate cancers. Large studies are currently taking place to determine if selenium supplements can prevent these cancers from occurring.
Studies have shown that daily consumption of red meat may double the risk of colon cancer. One explanation for this finding may be the methods used to cook or prepare the meat. Processed meats that are salt-cured, salt-pickled, or smoked have been associated with increased risk of gastric cancer, whereas meats that have been broiled or grilled at high temperatures have been shown to have increased levels of carcinogens that can increase colon cancer risk.
Other nutrition-related factors such as obesity and physical activity are part of the complex interaction of lifestyle choices that affect cancer risk. Regular physical activity seems to protect against cancer in the breast and colon, reducing risk by as much as 50 percent. Obesity has the opposite effect, increasing levels of hormones and other substances that encourage continued growth of cancer cells. For example, large fat deposits may be responsible for converting estrogen precursors to high levels of circulating estrogens. Unfortunately, current trends show that Americans are increasing their caloric intake, eating more high-fat convenience foods, and being less physically active. These trends may be related to more frequent meals away from home, sedentary lifestyle patterns, and increased media promotion of high-calorie foods.
Exposure to Sunlight Nonmelanoma skin cancer is the most common malignancy in the United States, representing 40 percent of all cancers. During the past thirty years, all types of skin cancers—melanoma, basal cell carcinoma, and squamous cell carcinoma—have increased dramatically. These skin cancers are caused primarily by overexposure to the sun’s ultraviolet rays.
Solar rays can damage skin even on cloudy days. With the continued thinning of the protective ozone layer, damaging rays are becoming more intense and dangerous. Over the short term, excessive sun exposure causes freckling, sunburn, and tanning, all of which are forms of skin damage. Rather than being a sign of good health, a tan signals the skin’s attempt to defend itself against solar radiation. Over longer periods of time, high levels of sun exposure can cause premature skin aging, wrinkles, and rough leathery skin, in addition to skin cancers.
Research findings suggest that intermittent intense sun exposure may increase the risk of malignant melanoma, the deadliest form of skin cancer. A history of five or more blistering sunburns can double the risk of melanoma. Because we accumulate much of our lifetime exposure to the sun prior to age eighteen, it is especially important to protect infants and children from sun overexposure.
Artificial sources of sunlight, including sunlamps and tanning booths, also increase the risk of developing skin cancer. Unfortunately, skin damage from any form of ultraviolet light is permanent and accumulates over a lifetime; however, it can be minimized by limiting sun exposure.
Geographic Patterns and Environmental Exposure The geographic patterns of cancer may provide important clues to the causes of cancer. Possible geographic risk factors include occupational exposures, regional dietary habits, ethnic background, and environmental exposures from the air or water. Additionally, geographic differences in mortality rates may reflect differences in access to medical care, such as screening, diagnosis, and treatment facilities.
Workplace exposure to chemicals such as coal-tar-based products, benzene, cadmium, uranium, asbestos, and nickel can greatly increase the risk of developing cancer. Up to 20 percent of bladder cancers may be due to chemical exposures in the aluminum, dye, paint, petroleum, rubber, and textile industries. Occupational exposures to radon and asbestos have been linked to lung cancer, and 1 to 2 percent of lung cancer deaths are attributable to air pollution.
Fertility Drugs and Oral Contraceptives Use of fertility drugs has been associated with an increased risk of ovarian cancer in some studies. However, infertility itself also increases ovarian cancer risk, thereby making it difficult to assess the independent risk associated with fertility drugs. The duration of use for some fertility drugs is restricted in order to prevent additional increases in ovarian cancer risk. Endometrial cancer is also increased in women who take fertility drugs, although separating the effect of the drugs from that of the infertility can be difficult in this case as well. Fertility drugs are not thought to increase the risk of breast cancer, cervical cancer, or colon cancer, although information in this area is somewhat limited.
The relationship between oral contraceptives and cancer risk has been controversial. Studies investigating the role of oral contraceptives on breast cancer risk have had conflicting results, but the majority of the evidence suggests that there is no increased risk of breast cancer in users of oral contraceptives. Ovarian cancer risk is decreased in oral contraceptive users in the general population, but the results are unclear for those who have an increased risk of ovarian cancer due to genetic susceptibility. Use of these medications has been shown to decrease the risk of endometrial cancer as well.
Hormone Replacement Therapy (HRT) For years, hormone replacement therapy, consisting of estrogen alone or in combination with progesterone, has been an option for women when they reach menopause. Potential benefits of hormone replacement therapy in postmenopausal women include protection of the bones from osteoporosis (bone thinning) and relief from menopausal symptoms such as hot flashes, vaginal dryness, insomnia, and mood changes. HRT was thought to have beneficial effects against heart disease as well; however, more recent evidence now indicates that heart disease is not decreased with the use of these medications.
Initially, hormone replacement therapy was the only tool that was available to treat these conditions. In recent years, newer drugs such as raloxifene (Evista) and alendronate (Fosamax) have become available to reduce the risk of fracture in those suffering from osteoporosis. These drugs are from a different class of medication than hormone replacement therapy and protect the bones in a different way. Nonhormonal therapies are also available to improve symptoms of hot flashes, insomnia, and mood changes.
Hormone replacement with estrogen alone has been shown to increase the risk of endometrial (uterus) cancer in women who have not had a hysterectomy. In the 1970s, women who received estrogen without progesterone were six to eight times more likely to develop endometrial cancer than women who were not on this medication. Since that time, doctors have prescribed HRT that includes low-dose estrogen and progesterone for women who have not had a hysterectomy. Progesterone counteracts estrogen’s negative effect on the uterus by preventing the overgrowth of the endometrial lining, thereby reducing the risk of endometrial cancer associated with taking estrogen alone. However, the addition of progesterone to estrogen replacement therapy dramatically increases the risk of breast cancer, as discussed below. A woman who has had a hysterectomy does not need progesterone and can receive HRT with estrogen alone.
Over the past thirty years, considerable research has examined the question of whether HRT affects breast cancer risk. The research falls into two categories: observational studies, which investigate differences in cancer rates in women who are already taking HRT as compared to those who are not; and clinical trials, which randomly assign women to use HRT or to use a placebo. Because observational studies may not account for all of the differences between women who use HRT and women who do not, clinical trials are considered to provide the strongest evidence.
Some of the early studies indicated that women who used high doses of estrogen alone had an increased incidence of breast cancer. More recently, analysis of data from the Nurses’ Health Study, an important large observational study comparing women who take hormone replacement therapy with those who do not, showed that prolonged use of estrogen increased the risk of breast cancer. After fifteen years of estrogen replacement, women had a 48 percent increased risk of hormone-sensitive breast cancer. After twenty years of replacement, there was a 42 percent increased risk in all types of breast cancer.
Other studies have shown that progesterone replacement may significantly increase the risk of breast cancer. One of the most important clinical trials in this area, the Women’s Health Initiative, was designed to test the effects of hormone replacement therapy on heart disease, breast cancer, and colorectal cancer risks. Over 26,000 postmenopausal women were enrolled in 1991 and randomly assigned to hormone replacement or placebo. Women who had previously undergone hysterectomy were given estrogen alone or a placebo, and women who still had a uterus were given an estrogen-progesterone combination or a placebo. Results from this study showed that the combination of estrogen and progesterone was associated with an increased risk of breast cancer and a decreased risk of colorectal cancer. The women who took estrogen only did not have a decreased risk of colorectal cancer, and the effect on breast cancer risk was uncertain.
Combination HRT with estrogen and progestin has been shown to increase breast density, as seen on mammograms. Studies have shown that women ages forty-five and older whose mammograms show at least 75 percent dense tissue are at increased risk for breast cancer. Increased breast density makes it more difficult to interpret mammograms; and follow-up procedures must sometimes be done, including mammograms, ultrasounds, and biopsies. The Women’s Health Initiative found that women who took estrogen alone also required increased numbers of mammograms.
Use of hormone replacement therapy in women who have a history of breast cancer or endometrial cancer remains controversial. At present, the standard of care is to use medications other than hormone replacement to treat menopausal symptoms and prevent osteoporosis in these women. Only in the most extreme situation of uncontrolled, severe hot flashes should estrogen replacement therapy be considered in this setting.
Sexual Activity Cervical cancer is caused by infection with a sexually transmitted virus called the human papillomavirus (HPV). Although most women are exposed to this virus in their lifetime, infection is usually transient. When this virus cannot be cleared by the body, cervical cancer may develop. Individuals who have multiple sexual partners or have a compromised immune system are more susceptible to the virus for this reason. HPV is also thought to play a role in cancers of the penis, vagina, and anus.
Risk Assessment
Just by virtue of becoming older, we all develop some risk for cancer. However, some people may be at even greater risk because of their combinations of modifiable and nonmodifiable risk factors. Individuals with a cancer risk that is three to five times that of the general population are considered at high risk. To identify people at high risk for cancer, risk assessment programs have been developed at many cancer centers. To enter a program, the participant completes a questionnaire that asks detailed questions about life history, personal and family medical history, work history, and lifestyle habits. A physical examination, blood work, and imaging studies may be part of the assessment as well. The questionnaire responses are analyzed to produce cancer risk scores, which are then interpreted. Participants receive results of the assessment, along with risk-reduction recommendations. These results are often forwarded to the participant’s primary care provider as well.
Some risk assessment questionnaires focus on specific types of cancer and ask specific questions to determine how well an individual fits in a specific model of cancer risk. One of the best-known models is the Gail model, which predicts breast cancer risk based on race, current age, age when menstruation began, age of first live birth, number of close relatives with breast cancer, number of breast biopsies, and the presence or absence of changes called atypical hyperplasia on breast biopsies. Most of these models have limitations (for example, the Gail model does not ask about ovarian cancer history or breast cancer history in second-degree relatives such as aunts, cousins, or grandparents; it may also be less accurate in predicting risk in non-Caucasian women). Therefore, models should be selected based on each individual’s situation in order to calculate risk as accurately as possible.
Several cancer risk assessment programs are available off the Internet. These programs may be less comprehensive than those available from cancer centers. Additionally, these programs cannot always answer questions you may have or individualize recommendations to your particular case. When using on-line programs, be sure to verify recommendations with your health care provider.
Hereditary Risk All cancers have a genetic component; the hallmark of all cancers is genetic instability. Although most cancers are sporadic (not inherited), about 10 percent occur because of hereditary predisposition. All men and women are born with cancer susceptibility genes, such as the breast cancer susceptibility genes BRCA1 and BRCA2. However, only people with alterations in cancer susceptibility genes are at higher genetic predisposition for cancer. Table 2 summarizes established risk factors for hereditary cancers and syndromes. Figure 3 illustrates a family pattern of breast cancer that is consistent with an inherited genetic predisposition.
Table 2. Established Risk Factors for Hereditary Cancers and Cancer Syndromes• Two or more first-degree relatives (parent, child, or siblings) with a specific cancer or cancers. These individuals can be on the mother’s and/or father’s side of the family.• One first-degree and two or more second-degree relatives (grandparents, aunts, uncles, grandchildren) with a specific cancer or cancers.• Evidence of transmission of cancer from generation to generation.• Unusually early age of cancer onset.• Clustering of the same types of cancers in close relatives.• Family members with cancer in paired organs (both breasts, both kidneys, both eyes).• Geographical heritage and ethnicity.
Genetic alterations associated with inherited predisposition to cancer can be identified through analysis of a blood or tissue sample. At this time, genetic testing is recommended only for individuals who have a personal or family history suggestive of an inherited cancer syndrome. The most effective way to determine if a heritable genetic alteration is in a family is by testing the individual who has had the cancer that fits the hereditary pattern. If a genetic alteration is identified in the individual who has had cancer, other individuals in the family who are at risk can be tested for the mutation identified in their family member. Genetic analysis should always be preceded by careful genetic counseling, which continues after determining gene mutation status. Identification of a genetic alteration may change recommendations for cancer screening, and chemoprevention medications or surgery options may be appropriate for these individuals.
Some genetic testing kits have become directly available to consumers. However, the implications of finding or not finding a genetic mutation can be profound. We do not recommend undertaking such testing without appropriate counseling from a professional with training and expertise in this area.
Screening and Early-Detection Guidelines
Despite all the advances in cancer treatment, the approach most likely to decrease cancer deaths is early detection. Catching cancer at its earliest stages can prevent spread to distant sites, which is the cause of most cancer deaths. Early detection depends on recognizing cancer’s warning signals and receiving prompt medical attention when signs and symptoms appear. The cornerstones of early detection are self-examination, examination by a health professional, and screening tests.
Self-Examination Breast self-examination was previously recommended for all women by the American Cancer Society. The most recent recommendations state that the risks and benefits of self-examination should be discussed with women, and that performing self-examinations infrequently or not at all is acceptable. This recommendation has been changed due to research that demonstrated no decrease in breast cancer deaths in women who performed breast self-examinations compared to women who did not. However, many clinicians still recommend breast self-examination because it promotes awareness of the breast, helps find breast changes early on, and has no cost. Women who perform this examination should be trained by a health professional.
Likewise, testicular self-examination is not formally recommended by the American Cancer Society. However, it also promotes awareness, helps find changes early on, and has no cost. Although testicular cancer is uncommon overall, it is one of the most common cancers in men ages twenty to thirty-five. Testicular cancer is highly curable when detected early.
Skin self-examination is another important component of health that is often overlooked. Men and women are encouraged to become familiar with their skin, including any freckles or moles. A mole that is asymmetric, has an irregular border, is more than one color, or is larger than the size of a pencil eraser should be evaluated by a dermatologist. In addition, any new skin lesions or changes in an existing mole or freckle should also be reported right away.
Clinical Examinations and Screening Tests Screening guidelines for any type of cancer depend on two primary factors: the age of the individual undergoing screening, and the individual’s risk factor profile. Risk factors can be due to lifestyle, family history, or other medical conditions. Table 3 summarizes the American Cancer Society recommendations for cancer screening for individuals at average risk of cancer. In the discussion below we will highlight some of the details behind the screening recommendations and note where controversies currently exist.
Table 3. American Cancer Society Recommendations for the Early Detection of Cancer in Average-Risk Asymptomatic PeopleWomen ages 20–39 Women ages 40 and overEvery 3 years Every year (to be done prior to mammogram)Every year (conventional Pap test) Every 2 years (liquid-based Pap test)• Pap test every 2–3 years (either type)• Pap test + HPV (human papillomavirus) testing every 3 yearsIf one or more of last 3 tests were not normal, follow guidelines for ages 18–30.Women who have had total hysterectomyMay choose to stop screening if 3 normal Pap tests and no abnormal tests in 10 yearsProstate-specific antigen (PSA) blood test and digital rectal examinationMen ages 50 and over with life expectancy of at least 10 yearsColorectal cancer screening (any of the following procedures):Men and women ages 50 and over• Fecal occult blood test**** or fecal immunochemical test, OREvery 5 years, starting at age 50• Fecal occult blood test and flexible sigmoidoscopy, ORFecal occult blood testing every year with sigmoidoscopy every 5 years starting at age 50• Double contrast barium enema, OREvery 5 years, starting at age 50Every 10 years, starting at age 50* Women should be informed of the benefits and limitations of breast self-examination (BSE). It is considered acceptable for women to choose not to do BSE or to perform BSE irregularly.** Cervical cancer screening with the Pap smear should begin three years after starting vaginal intercourse but no later than twenty-one years of age.*** Men should be informed of the benefits and limitations of PSA testing so that an informed decision can be made with the clinician.**** Samples should be obtained at home from three consecutive specimens. A single sample obtained during digital rectal examination by a clinician is not adequate.Source: American Cancer Society Guidelines for the Early Detection of Cancer, 2006
General Screening Regular health examinations should include inspection of the skin, mouth, lymph nodes, thyroid, testes, and ovaries for cancers and precancerous areas.
Breast Cancer Screening The American Cancer Society (ACS) recommends regular breast examinations by a clinician and mammography to detect breast cancer at early stages for women at average risk of this disease. For women between twenty and thirty-nine years old, examination should occur at least once every three years; for women over forty, clinical breast examination should take place annually.
Studies have shown that mammography, done on a regular basis, can decrease the number of deaths from breast cancer by as much as 30 percent. The ACS recommends that annual mammography should start at the age of forty for women at average risk. Although the appropriate starting age for mammography has been controversial in the past, more recent research has indicated that the benefit of mammography also applies to women between forty and fifty.
Use of digital mammography rather than film mammography may be beneficial for women who are under fifty, have dense breast tissue, or are premenopausal or perimenopausal. Increasing numbers of mammography units across the United States are adopting this technology. However, it is important to emphasize that no woman should defer screening with a mammogram due to a lack of access to digital mammography.
Several groups of women are considered to be at increased risk for breast cancer. Individuals with a history of radiation therapy to the chest, a strong family history of breast and/or ovarian cancer, or a known or suspected genetic predisposition to breast cancer are more likely to develop breast cancer than women in the general population. In addition, women with a personal history of breast cancer or breast lesions such as lobular carcinoma in situ (LCIS) and atypical hyperplasia also have a risk of having a second breast abnormality, which may be cancerous. Individuals in these groups may need to start breast cancer screening earlier, to have clinical breast examinations more often, or to have different screening procedures than women in the general population. In most cases, high-risk women should start screening when they are ten years younger than the age of diagnosis for their youngest relative with breast or ovarian cancer. Individuals who have a known genetic predisposition may require screening even earlier. These individuals may also be candidates for prophylactic surgery or chemoprevention to reduce their risk.
One newer screening procedure for breast cancer is breast magnetic resonance imaging (MRI). The primary use of breast MRI at this time is to assess women with a known genetic predisposition for breast cancer. Screening of these individuals must often start at a younger age, when the breasts are denser and harder to evaluate with mammography. Currently, breast MRI is not recommended for screening in the general population.
Cervical Cancer Screening Invasive cervical cancer is often preceded by precancerous changes in cervical tissue that can be identified with a Papanicolaou (Pap) smear. Screening for cervical cancer has been shown to reduce the number of deaths from this cancer. The ACS recommends that screening should start three years after a women starts having intercourse, or no later than age twenty-one. There are two types of Pap smears in current use, the conventional Pap smear and the liquid-based Pap smear. The conventional Pap smear should be performed on an annual basis, and the liquid-based Pap smear may be performed every two years. Once a woman has reached the age of thirty, less frequent screening can be considered if her last three Pap tests were normal. The Pap smear can be used alone or in combination with testing for human papillomavirus (HPV), the virus that causes cervical cancer. After the age of seventy, a woman may also consider stopping screening if she has recently had three consecutive negative Pap smears.
Women who have had a total hysterectomy for a noncancerous reason do not need to continue having Pap smears. However, if a woman has had a subtotal hysterectomy or has a history of cervical cancer or precancerous conditions, she should continue to have regular screening even after surgery.
Women who have a history of exposure to DES (diethylstilbestrol) are at increased risk of cervical and vaginal cancers. Continued screening with a Pap smear after hysterectomy is still recommended in this high-risk group. Other women who are at increased risk of cervical cancer include those who are immunocompromised due to organ transplant, chronic steroid use, chemotherapy, or infection with the human immunodeficiency virus (HIV). These individuals may require more frequent screening and do not have a designated age at which screening should stop.
Colon Cancer Screening Multiple procedures are currently in use for screening for colorectal cancer. For individuals at average risk for colon cancer, screening should start at age fifty. The ACS recommends any of the following options:
• Fecal occult blood test (FOBT) or fecal immunochemical testing (FIT) every year.
• Flexible sigmoidoscopy every five years.
• FOBT every year with flexible sigmoidoscopy every five years.
• Double-contrast barium enema every five years.
• Colonoscopy every ten years.
The option of combined FOBT with flexible sigmoidoscopy is preferred to either option alone. However, no one measure is preferred by the ACS for individuals at average risk of colon cancer. The National Comprehensive Cancer Network (NCCN) guidelines state that their preferred recommendation is colonoscopy, and that the barium enema is the least preferred option. The NCCN guidelines do not recommend use of FOBT or flexible sigmoidoscopy alone.
Individuals who choose to use FOBT for screening should perform at-home testing of three consecutive stool specimens. An FOBT of stool obtained during a rectal examination by a clinician is not considered sufficient for screening purposes. Also, dietary restrictions must be followed in order for this test to be interpreted accurately.
Fecal immunochemical tests (FIT) are also known as immunologic fecal occult blood tests or immunoassay fecal occult blood tests. Like the FOBT, this test assesses stool for the presence of a blood protein; however, it may be more accurate in determining if stool blood is present from the bowel rather than from another site higher in the gastrointestinal tract. The ACS has included this test as part of their screening recommendations, but the NCCN guidelines consider it an approach that is still under investigation at this time.
Other methods for screening the colon are under development. “Virtual colonoscopy,” also known as computed tomography (CT) colonography, uses a CT scan to evaluate the colon for polyps or cancer. Like conventional colonoscopy, this test requires preparation of the bowel with a laxative regimen, and air is inserted in the bowel in order to improve viewing during the procedure. If polyps are found on this test, conventional colonoscopy is done to remove them. Another screening alternative currently under study involves testing of the stool for DNA changes associated with colon adenomas and cancers. Cells from the lining of the bowel are routinely sloughed off into the stool, and several different panels of genetic mutations have been proposed to look for cancer and precancerous changes in these cells. At this time, additional study is needed before these techniques can be used routinely for screening purposes in the general population.
Individuals who are considered to be at higher risk for colon cancer include those with inflammatory bowel disease, those who have previously had a colon cancer, and those who have had a type of colon polyp called an adenoma. Women who have had uterine or ovarian cancer prior to the age of sixty are also considered to be at increased risk for colon cancer. These individuals require earlier and more frequent colon screening, which should be done by colonoscopy.
Colonoscopy is also recommended for individuals who have a family history of colon cancer or a family history that suggests a genetic predisposition to colon cancer. The age to start screening depends on the age of the youngest individual in the family who has had colon cancer. In most cases, high-risk individuals should start screening when they are ten years younger than the age of diagnosis for their youngest relative with colon cancer or a related cancer.
Endometrial Cancer Screening At this time, the American Cancer Society does not recommend screening for endometrial cancer for women at average risk. The guidelines do suggest that all women should be informed of the symptoms of endometrial cancer and should report any unexpected vaginal bleeding to their health care provider promptly.
Women at high risk of endometrial cancer due to a possible genetic predisposition based on a strong family history may be recommended to have screening with transvaginal ultrasound and/or endometrial biopsy. However, these procedures are not recommended for screening women who are at average risk.
Lung Cancer Screening Screening for lung cancer is not currently recommended for individuals without symptoms, regardless of smoking history. However, studies are being conducted to determine if screening can decrease the number of deaths from this disease. The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial is a 160,000-person study investigating whether chest X-rays can be used as a screening tool for smokers and nonsmokers. Spiral computed tomography (CT) scanning is another new tool that is being assessed for early detection of lung cancer in smokers. Nearly 50,000 current and former smokers have been enrolled in the National Lung Cancer Screening Trial, which is evaluating chest X-rays and CT scans as screening strategies.
Ovarian Cancer Screening Currently, screening for ovarian cancer is not recommended in the general population. Tests that have been proposed for screening include transvaginal ultrasound and a blood test called CA-125. These tests are not in use in the general population at this time because they can be abnormal when no cancer is present, and they can be normal even in the setting of cancer. The high rate of false positive results may lead to unnecessary surgical procedures, particularly in women under fifty years of age. Transvaginal ultrasound and CA-125 are currently being evaluated as screening measures for the general population in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.
Women who have a strong family history of breast or ovarian cancer are considered to be at increased risk of ovarian cancer. Screening with transvaginal ultrasound and CA-125 can be considered in these women, but the limitations of these tests should be discussed with a clinician before starting screening.
Prostate Cancer Screening Screening for prostate cancer remains a topic of considerable controversy. The American Cancer Society recommends that prostate cancer screening should be discussed with men ages fifty and over. Screening for prostate cancer consists of an examination of the prostate through the rectum and testing the blood for levels of prostate-specific antigen, or PSA. These tests should be performed on an annual basis for men who choose screening. However, men should also be informed of the limitations of PSA testing, since levels of the PSA protein can be elevated in conditions other than cancer and may be normal in the setting of cancer. Overall, about one-third of men with an elevated PSA level are found to have prostate cancer on biopsy.
Some groups have advocated starting screening with PSA testing in men at the age of forty and at average risk for prostate cancer. Men with a normal test at age forty would have the test repeated at age forty-five, and would start annual screening at age fifty. This approach is not universally accepted in average-risk men at the current time.
Two types of PSA tests exist, the complexed PSA and the total PSA. Either may be used, but it is important that the same test be used over time. Another test that can be helpful in assessing for prostate cancer is the PSA velocity, which is the average increase in PSA level in three measurements over eighteen months. Other forms of PSA testing are also in development but are not in current widespread clinical use.
Men who are considered at high risk for prostate cancer include African-Americans and those with a family history of prostate cancer. The ACS recommends starting screening at age forty-five in those of African-American descent and in those who have one close relative with a history of prostate cancer before the age of sixty-five. If an individual has more than one close relative with prostate cancer at an early age, screening should begin at age forty.
Preventing Cancer Through Lifestyle Choices and Clinical Trials
Studies are confirming what scientists, doctors, and many others have suspected for years—lifestyle does make a difference in our risk for developing cancer. As much as 60 percent of cancers may be the direct results of the lifestyle choices we make. Although many people have become more aware of cancer risk factors, many still resist changing their health habits. The success we can have in the fight against cancer hinges on two things that are within our power:
• increasing our understanding of the causes of cancer and cancer risk factors, and
• being willing to act upon that information to allow early detection of cancer and to implement lifestyle changes that reduce our chances of developing cancer.
Successful prevention and early detection require that we assume greater responsibility for our health. We also must work in partnership with health care professionals to make personal choices and risk-reducing decisions.
How Can You Reduce Cancer Risk?
Don’t Smoke Smoking cessation is the single most important change you can make to improve your health. Nicotine is an addiction, perhaps the most deadly form of drug dependence, and it is a difficult habit to break. But quitting is possible, as over 46 million ex-smokers in the United States can confirm.
Quitting smoking reduces risk for heart disease and cancer and lengthens life. For former smokers who have quit for ten years, the risk of lung cancer is half that of current smokers. This risk falls to as low as 10 percent for ex-smokers who have quit for thirty years or more. The risk for cancers of the mouth, throat, and esophagus lessens significantly five years after quitting, and the risk of developing bladder or cervical cancer also decreases after just a few years of being nicotine-free.
Individual plans and group support programs can increase the success rate in the attempt to stop smoking. Many health care providers offer practical counseling, including problem-solving and skills training, social support as part of treatment, and social support outside of treatment. The National Cancer Institute (NCI) conducts research on smoking cessation and works with other government agencies and nonprofit organizations to promote programs that reduce the rates of illness and death associated with smoking. Several NCI and American Cancer Society (ACS) publications provide tips on smoking cessation and dealing with secondhand smoke at work or in public places. These materials are available from the NCI-supported Cancer Information Service (CIS) at
800-4-CANCER (800-422-6237)
TTY (for deaf and hard-of-hearing callers): 800-332-8615
www.cancer .gov/aboutnci/cis
Another important resource is the National Network of Tobacco Cessation Quitlines, which can be reached at 800-QUITNOW (800-784-8669). This number will automatically route you to the quitline for your state or to the quitline for the National Cancer Institute if your state does not have a quitline.
Medications can also be used in combination with support and counseling. Nicotine replacement products deliver small, steady doses of nicotine into the body, which help to relieve nicotine withdrawal symptoms. These replacement products are available in a variety of forms, including patches, gum, nasal sprays, and inhalers. Bupropion (Zyban), a prescription drug approved by the FDA in 1997 to treat nicotine addiction, helps Wellbutrin to reduce nicotine withdrawal symptoms and the urge to smoke. This medication is generally well tolerated but should not be used by people with seizure conditions or eating disorders. Another newly approved medication for smoking cessation is Chantix, also known as varenicline tartiate. In addition to preventing cravings, this medication blocks the nicotine receptors in the brain to diminish satisfaction from nicotine. Your physician can help you determine if these medications are appropriate for you.
Finally, it’s important not to become discouraged if your first attempt at quitting is not successful. Most people try to quit smoking five to seven times before they can eliminate nicotine from their lives. Consider each attempt a learning experience that will build toward success in a future attempt, and don’t give up!
Watch Your Diet No diet is guaranteed to prevent cancer, but a diet low in fat with a wide variety of fruits, vegetables, and whole-grain products may reduce cancer risk. Table 1 lists the results of some major dietary studies in cancer prevention, and Table 4 summarizes cancer-risk-reducing dietary guidelines issued by the ACS and the American Institute for Cancer Research. Other dietary suggestions include using herbs and spices to season foods and limiting the consumption of salted foods and table salt, not eating food that has not been appropriately refrigerated, and not eating charred food. Studies from the NCI have documented that microwaving meats for two minutes and discarding the juices prior to cooking reduces the potential carcinogen content of these foods by as much as 90 percent. For people who follow the recommended dietary guidelines, supplements are not currently recommended for reducing cancer risk.
Table 4. Dietary Guidelines for Reducing Cancer RiskEat a variety of healthful foods, with an emphasis on plant sources.• Eat 5 or more servings of a variety of vegetables and fruits each day.• Choose whole grains in preference to processed (refined) grains and sugars.• Limit consumption of red meats, especially those high in fat and processed.• Choose foods that allow you to maintain a healthful weight.Adopt a physically active lifestyle.• Adults: Engage in at least moderate activity for 30 minutes or more on 5 or more days of the week. Moderate to vigorous activity lasting at least 45 minutes on 5 or more days per week may further enhance reductions in the risk of breast and colon cancers.• Children and adolescents: Engage in at least 60 minutes per day of moderate to vigorous physical activity at least 5 days per week.Maintain a healthful weight throughout life.• Balance caloric intake with physical activity.• Lose weight if you are currently overweight.Limit consumption of alcoholic beverages if you drink at all.Source: American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention, 2001Exercise Regularly Increased physical activity helps maintain an ideal weight and prevent obesity, a cancer risk factor. Weight control can reduce excess hormone production that may promote cancer growth. Exercise may also reduce the production of tumor-promoting prostaglandins, boost the body’s natural defenses, and strengthen the immune system to protect against cancer.
The American Cancer Society recommends that adults should engage in moderate exercise for at least thirty minutes a day, five or more days per week. Increasing the length of exercise to forty-five minutes or more may provide additional protection against breast and colon cancers. Children are recommended to exercise for at least sixty minutes per day for at least five days per week.
Ways to increase physical activity in daily life include using stairs instead of elevators, parking far away from your destination, and walking or riding a bike to work. Moderate exercise, such as brisk walking, helps burn fat, makes muscles firm, and builds bone strength.
Practice Safe Sex Use of condoms can prevent the transmission of human papillomavirus, the virus associated with cervical and other types of cancer. Know your partner’s history of sexually transmitted diseases, such as AIDS and HIV, and avoid having sex with multiple partners.
Limit Consumption of Alcoholic Beverages Because of the increased risk of cancers that are associated with alcohol use, the American Cancer Society recommends limiting alcohol use to two drinks per day for men. Women should limit their intake of alcohol to one drink per day due to slower metabolism of alcohol. A drink is 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor.
Avoid Excessive Exposure to the Sun’s Rays Although existing damage cannot be reversed, we can limit further insult to our skin by practicing sun safety. These safety measures include staying out of the sunshine during the peak hours of ten A.M. to four P.M., wearing protective clothing and hats, using sunscreen with a sun protection factor (SPF) of 30 or more, and avoiding artificial tanning devices. The higher the sunscreen’s SPF number, the longer the protection period; however, all sunscreen should be reapplied periodically, and particularly after swimming or perspiring heavily. People with light complexions, blue eyes, blond or red hair, or a tendency to freckle easily, need to be especially vigilant because they don’t have as much sun-protective melanin in their skin. Fundamental skin cancer prevention measures are summarized in Table 5.
Table 5. Skin Cancer Prevention and DetectionAvoid the midday sun between ten A.M. and four P.M.Wear a sunscreen with SPF 30 or greater.Cover up with protective clothing and a hat.Bring any moles to the attention of your doctor if they have one or more of the “ABCDEs”:A—asymmetry (one-half looks different from the other)C—color (different colors in the same mole)D—diameter (larger than a pencil eraser)E—evolving (a change in a mole)Exercise Caution in Taking Hormone Replacements Women should talk with their health care providers so they can make an informed decision about using hormone replacement therapy (HRT). HRT can be very effective in treating the symptoms of menopause and preventing bone loss, but other medications and habits may also be effective. For example, many women choose to reduce the risks of osteoporosis by exercising regularly, eating a balanced diet, and taking calcium supplementation and/or a bone-strengthening medication, such as raloxifene (Evista) or alendronate (Fosamax). Ultimately, each woman’s decision about whether to take HRT and the duration of its use must be an individual one based on information she has received from her health care provider. This decision should also be based on the woman’s personal and family history of cancer, heart disease, stroke, and osteoporosis. The current recommendation from the FDA is to use the lowest effective dose of hormone replacement therapy for the shortest duration of time.
Chemoprevention Chemoprevention involves the use of a dietary nutrient or drug to halt or reverse the process of carcinogenesis. At present, prescription chemoprevention medications are targeted only toward individuals with an increased risk of specific cancers. Several chemopreventive agents have been shown to be effective in large cancer prevention studies. Table 6 lists the results of some completed chemoprevention trials. These agents are not without side effects, so those taking them should receive close medical supervision.
Table 6. Results of Selected Completed Large Chemoprevention TrialsAlpha-Tocopherol, Beta-Carotene Lung Cancer Prevention Study (ATBC)Lung cancer in male cigarette smokers
Secondary target: prostate cancer in male cigarette smokers
Oral alpha-tocopherol (vitamin E) and beta-caroteneAlpha-tocopherol did not reduce lung cancer incidence; 18% higher incidence of lung cancer with beta-carotene and 8% more deaths.Alpha-tocopherol reduced prostate cancer incidence in men ages 50 to 69 by 32% and prostate cancer deaths by 41%.
Breast Cancer Prevention Trial (BCPT)Breast cancer in high-risk womenOral tamoxifen (Nolvadex) versus placeboTamoxifen reduced incidence of invasive breast cancer by 49%; similar reduction in noninvasive breast cancer. Approximately 50% increase in curable uterine cancer with tamoxifen.Beta-Carotene and Retinole Efficacy Trial (CARET)Lung cancer in heavy smokers and asbestos workersOral beta-carotene and retinol (vitamin A) versus placeboBeta-carotene and retinol groups had 28% more lung cancers diagnosed and 17% more deaths than in placebo group.Nutritional Prevention of Cancer (NPC) Chemoprevention TrialSecondary cancers in people with a history of skin cancerOral selenium (in yeast) versus placeboProstate, lung, and colorectal cancers were lower in selenium group; selenium group had 17% fewer cancers overall and fewer deaths from lung cancer.All cancers in male physiciansBeta-carotene produced neither benefit nor harm for cancer incidence or deaths, but only 11% of physicians were current smokers.Prostate Cancer Prevention Trial (PCPT)Finasteride (Proscar) versus placeboFinasteride reduced prevalence of prostate cancer by 25%; higher-grade prostate cancers were more likely in finasteride group.All cancers in female health professionalsLow-dose aspirin did not reduce risk of cancers, with possible exception of lung cancer. Vitamin E did not reduce cancer incidence or overall deaths.Study of Tamoxifen and Raloxifene (STAR)Breast cancer in postmenopausal women at increased riskTamoxifen (Nolvadex) versus raloxifene (Evista)Tamoxifen and raloxifene groups had similar rates of invasive breast cancer; noninvasive breast cancer was increased and uterine cancer was decreased in raloxifene group.All cancers and prostate cancer in male physiciansSecondary target: colon cancer
Vitamin E, vitamin C, beta-carotene, and multivitamin versus placebosSelenium and Vitamin E Cancer Prevention Trial (SELECT)Oral selenium, vitamin E, or both, versus placeboRecruitment closed 2004. Results anticipated in 2011.One of the main examples of chemoprevention is the use of tamoxifen (Nolvadex) to prevent breast cancer. Based on a 50 percent risk reduction in the Breast Cancer Prevention Trial, tamoxifen has been approved by the Food and Drug Administration (FDA) to reduce the risk of breast cancer in women who are at high risk. This drug can be a valuable tool for reducing breast cancer risk in women who have a strong family history of breast cancer or have a personal history of premalignant breast conditions; however, it is not recommended for women at average risk of breast cancer due to uncommon but serious side effects, including increased risk of blood clots, stroke, and uterine cancer.
More recently, results of the Study of Tamoxifen and Raloxifene (STAR) trial have shown that raloxifene (Evista) is another drug that can be used for breast cancer prevention. Both raloxifene and tamoxifen reduced the risk of breast cancer in postmenopausal, high-risk women by about 50 percent. In addition, both medications are highly successful strategies for reducing the risk of bone fractures in women. Women in the raloxifene group had fewer blood clots and fewer uterine cancers than those in the tamoxifen group. However, the women taking raloxifene had more noninvasive cancers, or carcinomas in situ, than the women taking tamoxifen. Although in situ cancers cannot spread to other parts of the body, it is uncertain why these lesions were more frequent in this group. These results suggest that raloxifene is a second option for risk reduction in postmenopausal women. The STAR trial did not include premenopausal women, so additional studies will need to be done to determine if raloxifene is also beneficial in women who have not yet undergone menopause.
Another important area of investigation in chemoprevention is the use of nonsteroidal anti-inflammatory drugs to prevent colon, breast, and other types of cancer in high-risk individuals. Regular use of these medications may decrease the risk of premalignant colon adenomas by as much as 45 percent in individuals who have already had a colon adenoma. Due to the cardiovascular effects associated with COX-2 inhibitors (types of nonsteroidal anti-inflammatory drugs), routine use of these medications for the prevention of cancer is not currently recommended outside of a clinical trial.
Human Papillomavirus Vaccine The human papillomavirus is an important cause of many cases of cervical cancer. Most women are exposed to this virus only for a brief period of time, but some women have persistent infection that can lead to cervical cancer. Gardasil, a vaccination against human papillomavirus, has recently been approved by the FDA. This vaccination is targeted toward girls ages eleven to twelve, but it may be administered to girls as young as nine and women as old as twenty-six. The vaccination consists of three shots given over a six-month period. Although this vaccination is highly effective in preventing most cervical cancers, women who have been vaccinated should still have regular screening with Pap smears.
Joining the National Fight Against Cancer
Community-Based Cancer Prevention and Control Initiatives The National Cancer Institute, the Centers for Disease Control and Prevention, and the American Cancer Society have launched large cancer prevention research studies and programs. These community-based efforts are designed to further our understanding of ways to prevent, detect, and control cancer.
Ongoing cancer prevention trials offer the public a way to participate in research, and advance the science of cancer prevention. These studies and programs target common cancer sites, such as the breast, lung, prostate, and colon. Listed below are examples of several ongoing cancer prevention studies taking place in multiple areas across the United States. If you are interested in participating in a cancer screening or cancer prevention trial, your physician may be able to provide you with information about studies in your area.
Vitamin D/Calcium Polyp Prevention Study This study will assess the effects of calcium and/or vitamin D supplementation on recurrence of colon adenomas. Individuals who have recently had a colon adenoma removed are eligible for participation, and approximately 2,500 participants will be enrolled in centers across the country. The prevention target is new colon adenomas seen on follow-up colonoscopy, which is done three to five years later.
Study of Selenium in Patients with Adenomatous Colorectal Polyps This trial is studying the micronutrient selenium to determine if it can effectively prevent the recurrence of colon adenomas in individuals with a history of adenomas. In order to participate, individuals must have a history of having a colon adenoma removed within the last six months. Approximately 1,600 participants will randomly be assigned to selenium or placebo, and the primary assessment will be the rate of adenoma recurrence after 2.5 to 5 years.
Computed Tomographic Colonography (Virtual Colonoscopy) Screening for Colon Cancer This study will investigate the use of computed tomography (CT) scans in screening for colon cancer. Participants must be at least fifty years old and due for a screening colonoscopy. Colonoscopy will also be performed for participants as part of the study. Multiple sites are participating in this study across the United States.
Cancer Control Advocacy Legislative action and public policy can complement research and education to reduce cancer incidence and deaths. To accomplish this goal, people need to speak out and demand action from Congress and from state and municipal bodies. Such public advocacy has already been successful. For example, mammography facilities in the United States are now required to meet strict accreditation and inspection guidelines. Smoke-free public buildings and work sites are commonplace. The government budget for breast cancer research has increased, largely from results of demands by grassroots organizations. Medicare now reimburses for screening mammography.
Additional public advocacy is warranted for prohibiting sales of tobacco products to youth and increasing penalties to vendors who sell to minors. Increasing access to and insurance coverage for early-detection and screening procedures is still on the horizon.
Advocacy is taken seriously by the NCI. The Director’s Consumer Liaison Group advises and makes recommendations to the NCI director from the perspective and viewpoint of cancer consumer advocates on a wide variety of issues, programs, and research priorities. The committee serves as a channel for consumer advocates to voice their views and concerns.
Resources on the Internet
American Cancer Society:
www.cancer .org/docroot/home/index.asp
Cancer Research and Prevention Foundation:
www.preventcancer .org/index.cfm
National Cancer Institute (Information on clinical trials):
www.cancer .gov/clinicaltrials
My Pyramid (Information for a healthy diet):
www.choosemyplate .gov
Smoking Cessation Information:
www.smokefree .gov
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