mercredi 23 octobre 2013

Childhood Cancers – Causes, Signs and Symptoms, Diagnosis and Treatment

Cancer in children is a rare disease. For every 120 adults who develop cancer, there is 1 child. Yet next to accidents, cancer is the second most common cause of death in children between the ages of one and fourteen. In the United States, about 12,400 children and adolescents younger than twenty years will be diagnosed with cancer each year, and 1,400 will die of cancer. Recent evidence suggests that the incidence of cancer in children has increased approximately 1 percent per year during the past twenty-five years. However, the overall mortality rate in children younger than fifteen has decreased by 38 percent.

Childhood cancers are different from those in adults. The growth pattern is different and tumors react differently to treatment. Most important, the problems seen in a child differ from those of an adult.

Fortunately, with the development of new drugs, new treatment methods, and better diagnostic tools and the involvement of multidisciplinary medical teams, the outlook for childhood cancers has improved dramatically over the past few decades. Currently, the overall cure rate for the United States for children and adolescents with cancer has exceeded 75 percent.

Types The most common childhood cancer is leukemia, accounting for about one-third of all cancers seen. The most common types in children are acute lymphoblastic leukemia and less frequently, acute nonlymphocytic leukemia. A smaller number of children may develop chronic granulocytic leukemia.

Brain tumors—gliomas, medulloblastomas, and ependymomas—are the second most common type of cancer in children. A new term has recently been designated for certain types of brain tumors—PNET, which stands for primitive neuroectodermal tumors.

Some cancers seen in children are rare in adults. A cancer of the sympathetic nervous system known as neuroblastoma may occur in the adrenal glands located on top of the kidneys or may originate anywhere there is a particular kind of nerve ending—in the chest, the abdomen, the pelvis, and, rarely, other sites. A cancer of the kidney known as Wilms’ tumor is also particular to children, occurring most commonly in children two to four years of age and rarely in those over sixteen. It may occur in one or both kidneys.

Other childhood tumors that are uncommon in adults are a tumor of the membrane at the back of the eye, the retina, called retinoblastoma; a muscle tumor called rhabdomyosarcoma; teratomas, which are tumors of young cells known as germ cells; and a tumor of the liver known as hepatoblastoma.

Bone tumors such as osteogenic sarcoma, Ewing’s sarcoma, and chondrosarcoma occur in children, particularly in teenagers. Histiocytosis X, or Langerhans cell histiocytosis, is not a malignancy but is often cared for by physicians who specialize in pediatric cancer therapy.

Children, like adults, develop lymphomas known as Hodgkin’s disease and non-Hodgkin’s lymphoma. They may also have tumors of the liver (hepatomas), skin cancer (melanoma, which is rare), and cancers of the thyroid and adrenal glands and blood vessels.

Over 80 percent of cancers in adults develop in the glands or lining tissues of the breast, lung, or intestinal or urinary tract and are called carcinomas. Leukemias, central nervous system tumors, and lymphomas account for over 60 percent of all the cancers diagnosed in children. About 15 percent of cancers of children are malignancies of muscle, bone, supporting tissues, or blood vessels and are called sarcomas. The types of cancers seen in children, therefore, differ from those in adults not only in name, but in their microscopic appearance.

What Causes It We do not know why children develop cancer. Occasionally there are clues from the environment or from a genetic inheritance pattern that a child may be at risk. But specific causes have not been identified. However, children with certain diseases do have an increased incidence of cancer (see “Risk Factors,” in this post).

For more than thirty years, there have been reports of “clusters,” or concentrations, of childhood cancer developing in certain geographic areas. There were clusters of children with leukemia in Niles, Illinois, in 1963; in Woburn, Massachusetts, in 1979; and in central California in the early 1990s. But physicians have not been able to determine the significance of these clusters.

It is believed that children are more likely than adults to develop leukemia as a result of exposure to radiation. Children exposed to the radiation of the atomic bomb blasts in Japan had an increased risk of acute leukemia in childhood, with the peak occurring about five years after exposure. A higher incidence of leukemia in children exposed to radiation after the accident in Chernobyl, Ukraine, has occurred. Radiation therapy is useful in the treatment of many cancers in children, but there is a risk that children cured of their first cancer may develop a second one partly related to the use of radiation therapy.

A number of cancer-causing chemicals and industrial processes are all around us. Their role in causing childhood cancers is the subject of ongoing research.

There has also been publicity about electromagnetic waves produced by high-tension power lines as a possible cause of cancer in children. Recent reports have refuted the claim. In recent years, new information has been released about causation with discoveries in the field of molecular genetics. Oncogenes (tumor-promoting genes) have been found in certain childhood cancers. Anti-oncogenes (tumor-suppressing genes) have been found in association with other childhood tumors.

For parents, it is frustrating to acknowledge that there is very little they can do to protect their children from environmental or genetic factors. Research is continuing, however, and one day, we may have better means of protection.

Risk Factors

The cancer rate for African-American children in the United States is about 80 percent of that seen in white children; children who are black do not have the same incidence of common cancers such as acute lymphocytic leukemia and lymphomas as children who are white. Black children rarely have Ewing’s sarcoma, but there is a suggestion that they have a higher incidence of Wilms’ tumor, retinoblastoma, and the bone tumor known as osteogenic sarcoma.

Several cancers in children—leukemia and Wilms’ tumor, for example—peak in incidence between the ages of two and four years. Others, such as lymphoma and bone cancer, have a peak incidence in older children.

At Significantly Higher Risk

• Previous exposure to radiation.

• Children who do not have an iris—the colored circle in the eye—have a higher incidence of developing the kidney cancer called Wilms’ tumor.

• Children whose bodies are bigger on one side than the other (hemihypertrophy) have a higher incidence of Wilms’ tumor.

• Males with an undescended testicle (cryptorchidism) are at higher risk for testicular cancer.

• Children with the skin disease xeroderma pigmentosum have a higher risk of developing skin cancer.

• Children with the immune disorder ataxia telangiectasia, Down’s syndrome, Fanconi’s anemia, and Bloom’s syndrome are at higher risk for developing leukemia.

Screening

A number of tests screen for cancer in adults, but very few such tests exist for children. In Japan, Quebec, and some other parts of North America, there is an attempt to screen the urine of very young children to detect the presence of abnormal amounts of the chemical group known as catecholamines in the hope that earlier detection of neuroblastoma will result in an improved cure rate.

The child with a risk factor for developing cancer should be evaluated carefully by his or her physician. The screening may be as simple as a blood test in an identical twin of a child with leukemia or a series of ultrasound examinations of the abdomen for many years in a child with hemihypertrophy.

Common Signs and Symptoms

Many of the symptoms and signs of childhood cancers are very common to other illnesses, and only health professionals with sufficient training will be able to tell whether a complaint is due to a normal childhood disease or a rare disease such as cancer.

Tiredness and paleness are usually the result of nothing more than the flu but could also signal the onset of leukemia. Fever is often noted in a child with infection, but recurrent fever, especially with bone pain, may be a symptom of leukemia or a bone tumor.

Children who have headaches with vomiting may have nothing more than an upset stomach, but recurrent headaches with vomiting that do not go away with time require a physician to make sure there isn’t a brain tumor.

Children who have a mass in their abdomen are probably just constipated, but the mass could be Wilms’ tumor, neuroblastoma, lymphoma, or a liver tumor. Lumps in the neck are usually due to an infection, but if they don’t respond to antibiotics, a lymphoma is a possibility. Drainage from the ear is usually due to an ear infection and only rarely due to some tumor.

Weight loss is rare in a young child, although it is something teenagers often desire. If the weight loss is not controlled, however, there may be psychological reasons involved or a lymphoma such as Hodgkin’s disease.

Obviously, children’s complaints are usually the result of normal childhood ailments. But when parents are concerned that their child has a persistent problem, they should take him or her to the doctor. The findings of a physical examination may suggest that special tests are necessary to discover whether the child does in fact have a cancer.

Some signs and symptoms are not common. Any newborn child with a cat’s eye—a white dot in the center of the eye—should be seen by a physician, since the dot may indicate a retinoblastoma. It is also very rare for children to have blood in their urine, so any child with this complaint should be seen by a physician. Blood in the urine may be the result of an infection but may also be caused by Wilms’ tumor.

Diagnosis

Physical Examination

• A complete physical examination should include the groin area, the testicles, the skin, and the nervous system. A rectal examination may also be performed to rule out a tumor in that area.

• An enlarged liver and/or spleen or a mass in the abdomen may indicate a tumor.

• Lumps in the neck that are firm, nonmovable, and have not responded to antibiotics may be due to lymphoma, leukemia, and other cancers.

• The eyes may be examined, a procedure that requires the child’s cooperation. A special instrument for looking into the eyes (ophthalmoscope) lets the physician see if there is increased pressure in the brain, which is often due to a brain tumor.

Blood and Other Tests

• A simple blood test examining the red cells, white cells, and platelets will usually let the doctor decide whether acute leukemia is a serious possibility.

• A special type of urine test will be helpful in cases of suspected neuroblastoma.

Imaging X-rays and CT and MRI scans help the physician decide whether there are tumors in the brain, chest, abdomen, or extremities.

Endoscopy and Biopsy Some suspected tumors might have to be biopsied for a definitive diagnosis.

Staging

Many so-called solid tumors of childhood—those that do not develop in the blood—are often staged by a system that classifies the disease by whether the tumor can be completely removed surgically. The involvement of lymph nodes and spread to distant sites are also considered. Greatly simplified, Stage I usually refers to local disease that can be entirely removed by the surgeon. Stage II could still be a local disease that may also be removed but has extended beyond the immediate area of the tumor. Stage III disease tends to be more extensive but localized in a particular region of the body, and Stage IV disease is widespread, having spread through the blood or lymphatic system to produce new tumors (metastases) in other organs.

Acute lymphoblastic leukemia (ALL) is categorized as standard (low) risk and high risk, according to its potential risk of recurrence (relapse). Two major factors—age at diagnosis and white blood cell (WBC) count—are used for staging of ALL. The child with low-risk leukemia has an excellent chance of responding to therapy in the long term and the best chance of being cured. On the other hand, a child with high-risk leukemia may still respond to therapy and may still have a good chance of being cured, although he or she may need more intensive treatment.

Treatment Overview

The treatment of a child’s cancer may involve surgery, chemotherapy, radiation therapy, immunotherapy, and various supportive measures.

The special problems seen with childhood cancers mean that a child should not be treated only by a single physician. A team approach is required, with physicians assisted by many specialists, including psychologists and experts in nursing, social services, nutrition, physical therapy, occupational therapy, pharmacy, child life, and other fields. They should all be involved in designing the appropriate treatment and support program for the child and his or her family.

This kind of multidisciplinary approach can be accomplished only in a “center of excellence,” an approved pediatric cancer specialty unit. In the United States and Canada, various cooperative groups have merged to form a single Children’s Oncology Group (COG). Nearly 95 percent of children younger than fifteen with cancer receive their care at institutions affiliated with COG. Families of adolescents and young adults between sixteen and twenty-one are encouraged to seek a referral to one of these centers.

When a child is diagnosed with cancer in most of these centers, his or her case is presented to a tumor board, a meeting of physician specialists, subspecialists, and other members of the treatment team who evaluate the child, discuss the options, and agree to a proposed treatment plan.

Clinical Trials Cancer in children is rare. Each year in the United States, slightly over 3,000 children develop leukemia, and 2,000 develop various kinds of brain and nervous system tumors. Approximately 500 children develop Wilms’ tumor. Rhabdomyosarcoma, retinoblastoma, osteosarcoma, and Ewing’s sarcoma are less common. Obviously, if progress is to be made on more effective treatment methods, physicians throughout the nation have to work closely together in designing therapies.

Accordingly, all children with cancer who are treated in a center of excellence are asked to participate in a clinical research program. It is because of these programs that we have made such gratifying progress in the treatment of childhood cancers over the past few decades. Parents and their children are encouraged to participate in them.

Phase III Trials A child may be a candidate for a research program known as a clinical protocol, which will compare one form of treatment to another. The research protocol will be explained, and parents will be asked to agree to participate with their child in the program.

The program may involve “randomization,” meaning that which one of the several potentially effective treatments the child receives will be decided by chance. Parents are often upset when they learn that if they participate in a research program, the decision about which treatment their child will receive will not be chosen by their child’s physician. But parents should understand that their child’s physician would not participate in the program unless he or she were comfortable that all the various treatment choices were reasonable and appropriate and offered the child an excellent chance of attaining a response.

The initial treatment programs designed to answer which treatment program is best are often known as Phase III studies. Sometimes a research protocol is not available, and then the physician chooses the best-known effective treatment available for the disease and presents it as the proposed treatment plan.

Most children respond very well to the initial treatment of their cancer. The opportunity to cure a child with cancer may be as great as 80 to 90 percent for some children with acute lymphoblastic leukemia and Wilms’ tumor, but unfortunately less in most other tumors. The patient’s physician will be able to describe in detail the treatment being proposed and the chances of the child being cured.

Phase II Trials Unfortunately, not all children respond to therapy. Even those who do may relapse. These children may still have their disease controlled or cured.

Children with recurrent disease or with an extraordinarily challenging cancer may be candidates for Phase II protocols, treatment programs in which the dose and many of the side effects of a particular drug or treatment are unknown. The goal of treatment is to determine how effective the therapy is for certain kinds of childhood cancer.

If this kind of study is available and the child and parents are asked to participate, the physician will describe in detail the proposed treatment, the risks involved, and the possible advantages of the child’s working with the physician in this research approach.

Phase I Trials Occasionally, there are drugs to be tested in children for the first time. Research protocols involving new drugs are called Phase I studies. The goal is to find the appropriate dose to be used, with the hope that the children will respond to the treatment.

Investigational Treatments There is a long list of investigational protocols for most childhood cancers. These protocols are devised after close cooperation and collaboration among investigators working in specific centers of excellence affiliated with the Children’s Oncology Group.

The protocols may involve new drugs that have rarely been used in children or they may involve new types of radiation therapy such as high-dose radiation given in a series of small doses (fractionated radiotherapy) or Proton irradiation—a high-energy radiation given to discrete tumors, thus sparing the surrounding normal tissues.

Most pediatric cancer experts do not consider such programs experimental but rather investigational. They consider these protocols an opportunity for the child and his or her family to participate on the frontier of medicine. A child with cancer should be treated with the methods being devised today that will possibly improve the chances for a cure tomorrow.

Bone Marrow Transplantation Several treatment programs for childhood cancers use the concept of bone marrow transplantation, although with many concerns, as it is still considered an investigational treatment under evaluation (see this post, “Bone Marrow and Blood Stem Cell Transplantation”).

Allogeneic bone marrow transplantation—which involves giving the child who has cancer bone marrow taken from a donor, ideally a close relative such as a brother or a sister—is being used very often in children with acute nonlymphocytic (granulocytic) leukemia. It is also used quite frequently in children with acute lymphoblastic leukemia who have had a relapse.

In autologous bone marrow transplantation, the patient’s own bone marrow is used. A portion of the bone marrow is stored in the laboratory while the patient receives treatment, and then returned in the form of an intravenous infusion of bone marrow cells. These cells circulate throughout the body and settle into the bone marrow compartment from which they came. They subsequently grow and regenerate the bone marrow.

Newer approaches have also recently been devised. It is now known that bone marrow cells may circulate throughout the blood, and machines that can remove some of the circulating cells are being developed, raising the possibility of removing bone marrow cells from a vein rather than by drawing them out of bones through a needle.

In high-dose rescue therapy—also called autologous rescue—the patient’s bone marrow cells are stored while high-dose chemotherapy is given. The cells are then reinfused. The higher doses of chemotherapy may kill cancer cells more effectively but might also seriously damage the bone marrow if rescue therapy were not performed.

Supportive Therapy

Throughout the course of the child’s treatment, there will be a need for many kinds of support therapies:

• Transfusions of blood products, platelets, and white cells may be needed.

• Infections are common in children and may require specific antibiotics. Exposure to contagious disease is likely to occur, so the child may require specific gamma globulin.

• Supportive measures can include nutritional support such as artificial feedings through a vein (hyperalimentation) or enteral feedings through nasogastric or nasojejunal tubes. Access to a vein may be a problem, so central venous catheters are often used, such as the Broviac or Hickman catheters or the Port-a-Cath.

• Drugs, other agents, and psychological support techniques may be necessary to help children with anticipatory nausea, or nausea and vomiting after radiation or chemotherapy treatments.

Treatment Follow-Up

Whatever the treatment a child with cancer is receiving, he or she will be followed closely by the pediatric oncologist, other physician specialists, and the multidisciplinary team assembled to work with both the child and the family.

Since the child will be on a research protocol in most cases, the physician will be able to outline for the parents an organized plan for follow-up evaluations. These may include specific liver function tests, urine tests for children with neuroblastoma, specific X-rays, psychological testing, and other tests that can help follow the progress and effects of the disease and the response to treatment.

Even when a child finishes a course of treatment, he or she will require long-term follow-up by a pediatric cancer expert. This is not only because some treatments have long-term side effects, but also because children who are cured of a first cancer do have a small risk of developing a second one. So even the child who finishes therapy and is apparently cured should be followed by a specialist for the rest of his or her life.

Some of the Most Important Questions (and Answers) for You and Your Child

For the Child

What do I have?

It is now known that children do better when they are told the truth about their illness. We no longer hide from them the fact that they have cancer. We explain the nature of their disease, tell them about the therapy, and ask them to work with physicians and other experts to help them attain a cure. Honesty is the best way to help a child face the serious problems of the disease.

Why did this happen?

We do not know why children develop cancer. Although there are some environmental or genetic clues that a child may be at risk, specific causes have not been found in the same way that streptococcus bacteria causes a sore throat.

It is important for the child—and the parents—to realize that having cancer is not a punishment. Cancer occurs in children throughout the world. Parents should not feel guilty. Their strength and optimism is needed by their child, who is facing a serious disease and requires their support to conquer the cancer and win the battle for his or her life.

Will my hair grow back?

Most children lose their hair temporarily after chemotherapy. In rare cases, such as when very intensive radiation treatments are used, hair may not grow back. But in most cases, the child develops a beautiful head of hair after the temporary period of baldness. Many children use wigs to help them with their self-image during these periods.

What will happen with the acne and chubby face I have when I’m getting prednisone treatment?

Steroids such as prednisone and dexamethasone (Decadron) do cause a temporary gain in weight and may cause facial acne. Once these drugs are stopped, the weight gain and the puffiness of the face disappear and the skin improves dramatically. There are very few if any permanent side effects of these treatments. Occasionally, stretch marks may be seen in the abdomen, but otherwise the child’s complexion and facial configuration do return to normal.

For the Parent

When will I get my child back?

When a child is diagnosed as having cancer, he or she may experience a change in personality. The child’s spirit, temperament, and behavior pattern may change substantially. The initial treatment may require a long period of hospitalization, and even if the child is seen as an outpatient, there are frequent visits that may include uncomfortable injections. It may take a while before the family pattern gets back to normal. Parents have to be patient. It may take several months before their child’s behavior returns to what it was before the illness.

How about school?

For a child, school is the normal working environment. Just as an adult wishes to return to work and continue his or her normal activities, so does the child wish to get back to the normal routine. Multidisciplinary programs will offer the family support to work with the school system so that the child with cancer can reenter his or her normal environment. School administrators, teachers, and others are becoming more familiar with the fact that children in their classrooms may be undergoing cancer therapy. For the most part, school personnel are understanding. They can develop flexible schedules that permit the child to take advantage of the maximum number of educational opportunities while continuing with treatment programs.

How can we help relieve the nausea, vomiting, and other side effects of chemotherapy?

Unfortunately, many cancer chemotherapy drugs cause nausea, vomiting, mouth sores, constipation, skin rashes, sore eyes, and generally a lower resistance to infection. Prompt attention should be given to the constipation caused by vincristine (Oncovin).

Medications are available to help the child tolerate these side effects. Occasionally, the medications themselves will cause tiredness.

What are the long-term effects of therapy?

A number of long-term effects of childhood cancer therapy are currently being studied. Radiation therapy to the brain may leave some children with certain deficits in intellectual or motor development, which is why psychometric testing is so important as part of the general treatment follow-up.

Some children may have growth problems. Some may have an organ abnormality because of the effects of radiation therapy or surgery. Rehabilitation may be necessary, such as a new bladder to urinate or an artificial limb. Some drugs also affect the way organs such as the lungs and heart work. Children with cancer may have to be followed for many years to discover whether some of the treatments used to cure the disease will result in organ problems later on in life.

What are the chances of my child being cured?

A physician will be able to explain to the child and the parents the chances of attaining not only remission—control of the disease—but actual cure. These “chances” are statistical averages, however, and children are not statistics. A family can concentrate on the negative or on the positive. As long as there is an opportunity for a cure, it makes more sense to concentrate on the positive and focus the family’s energy on the possibility that their child will be cured and will grow up and live a normal life span. Most children with cancer are cured and become healthy adults, parents, and productive members of society.

What happens if my child does not respond?

There are children who do not respond to treatment and unfortunately the disease may take their lives. If it appears that this is going to happen, the child’s physician will be the first to explain to the parents the nature of the problem and the reason why it looks as though the child is not going to have his or her life saved. The health care team will make sure that the child is comfortable and treated in a kind, caring manner. The physician and other members of the multidisciplinary team will work with the family to provide emotional, psychological, and spiritual support.

“Climbing the Mountain”

For the child with cancer and his or her parents, there are two basic choices: They can choose the pessimistic road, which goes downhill with the expectation that the cancer will cause the child to die. Or they can choose the optimistic road, an admittedly uphill road leading to the top of a mountain.

The curves in the mountain road are many. They represent problems that may occur during treatment, such as

• recurrent admission to the hospital for fevers and infections requiring intravenous antibiotics;

• side effects of chemotherapy, including hair loss, nausea, vomiting, mouth ulcers, stomach ulcers, blood in the urine, and rectal ulcers;

• side effects of radiation therapy, including hair loss, skin irritation, nausea, vomiting, and fatigue;

• side effects of surgery, including discomfort and organs that do not work in a normal way;

• allergic reactions to blood, blood products, or antibiotics;

• changes in plans to attend school or social functions or to go on family trips;

• therapies that are only partially successful; and

• special kinds of treatment, including investigational protocols and bone marrow transplantation.

Each and every one of these problems or curves can be difficult to manage. But each and every one has been managed successfully by other children and other families of children who have cancer. Sometimes, a curve can’t be maneuvered and it is necessary to move onto the pessimistic road. But for most children with cancer, the curves can be managed and the climb up the mountain is successful. Treatment may last for six months or a year, or even two, three, or more years, but the top of the mountain can be reached.

The goal for all children with cancer is that they will be cured. More and more children with cancer are attaining this goal and are growing up to be healthy adults. So children and their parents should be optimistic. Knowing that cure is a possibility, each child and his or her family should plan on climbing the mountain and reaching the top. On the top, the sky is blue and the sun is shining.

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