Cancers involving muscle, bone, blood vessels, and other supporting tissues in the body are termed sarcomas. They are different from carcinomas, which are malignancies of the tissues that line or cover the body’s internal organs and passageways. Of all the cancers of solid tissues, children most frequently have sarcomas. Carcinomas are much more frequent in adults.
Types Rhabdomyosarcoma of muscle is the most common soft-tissue sarcoma in children, accounting for slightly more than half of all soft-tissue sarcomas. Many different tissue types account for the rest. They may be located in nerves or their covering sheaths (e.g., malignant peripheral nerve sheath tumors), blood vessel walls (e.g., angiosarcomas), joint linings (e.g., synovial sarcomas), or fatty tissues (e.g., liposarcomas).
Other sarcomas in children occur in or around bone. The most common is osteogenic sarcoma, which is a cancer of the bone tissue itself. The second most common is Ewing’s sarcoma. Although Ewing’s sarcoma occurs in or around bone, this tumor probably originates from the nerve tissue in these locations.
In the United States, an estimated 500 to 700 children under eighteen are diagnosed with rhabdomyosarcoma each year. Osteosarcoma strikes 450 to 600 young people, and Ewing’s sarcoma affects 350 to 400.
The rarity of sarcomas in children and adolescents emphasizes the need for treatment by a small number of physicians in a limited number of children’s cancer centers so that the most experienced physicians and expert care can be available. This also allows the most rapid accumulation of knowledge about treatment, since it facilitates cooperative studies between institutions. The great progress made in treating these tumors over the past two to three decades has in large part been due to cooperative clinical studies designed to find the most effective treatments.
What Causes It Examination of some types of sarcoma cancer cells has shown that a transfer of genetic material has taken place from one chromosome to another within the cell; this is called a translocation. We do not know why this transfer occurs, but it most probably results in the cancer. Other sarcomas may have genetic changes, called mutations, that drive the cell to grow and spread. All of the genetic alterations associated with sarcomas are seldom inherited.
Rhabdomyosarcoma
This tumor is almost always found in muscle areas that can be controlled voluntarily, such as the eye, bladder, arms, and legs. (Involuntary muscles are those that work automatically, such as the heart and the wall of the intestinal tract.) The head and neck area is the most common site, followed by the genitourinary area—the vagina in girls, near the testes or prostate in boys, and the bladder. The trunk, chest, and back of the abdomen are less frequently involved.
How It Spreads The tumor can spread directly into surrounding tissues, through the lymphatic vessels to regional lymph nodes, or through the bloodstream to the lungs, bone, bone marrow, and central nervous system.
Symptoms Symptoms vary according to the location. The tumor is often painless but produces symptoms when it impinges on nearby nerves or tissues. The first sign may be a painless lump in or around the eye, on a limb, or in the abdomen. A small mass may extrude from the vagina. When the tumor is in the bladder, there may be difficulty urinating or blood in the urine. Back or abdominal pain or jaundice can develop when the tumor is large enough to cause pressure or obstruction of abdominal organs.
Diagnosis and Staging Other entities can produce the same physical signs and symptoms as rhabdomyosarcoma, so a biopsy is always necessary to establish the diagnosis with certainty. X-rays, CT and/or MRI scanning, and bone marrow examinations are used to determine the extent of the disease.
Treatment Overview Surgery, radiation, and chemotherapy are combined in the treatment of this diverse tumor. The order in which they are given, which combination of drugs is used, and how much radiation is delivered vary according to the location, tissue type, and extent of the disease. Putting together the many variables about each tumor—tissue subtype, surgical result (Group) and location (Stage)—allows a specific treatment plan based on risk and the most accurate estimate about outcome to be formulated.
Treatment by Risk
Low-Risk Patients
No evidence of tumor remaining after surgery, favorable tissue subtype, and favorable location.
Standard Treatment Surgery, followed by chemotherapy and, possibly, radiation. The tumors with the best outlook are those around the eye or testes that can be completely removed and have no evidence of spread. Patients are usually treated with vincristine (Oncovin) and dactinomycin (Cosmegen).
The next best outlook is for tumors in the head and neck and pelvic areas, other than the bladder and prostate, that can be completely removed. Chemotherapy with agents such as vincristine, dactinomycin, and cyclophosphamide (Cytoxan) may be used and radiation may also be used.
Five-Year Survival 75 to 95 percent
Intermediate-Risk Patients
Tumor remaining after surgery and/or unfavorable tissue type and/or unfavorable location, but not spread to other sites.
Standard Treatment These tumors are treated with a combination of chemotherapy and radiation therapy.
Five-Year Survival 70 percent
High-Risk Patients
The tumor has spread to distant sites at the time of diagnosis.
Standard Treatment New combinations of drugs are used in the hope of finding effective agents that are then combined with standard combinations of vincristine (Oncovin), dactinomycin (Cosmegen), and cyclophosphamide (Cytoxan) and radiation.
Five-Year Survival 20 percent
Recurrent Cancer
Several options are available if there is a relapse or inadequate response to initial therapy. Intensive treatment with radiation and chemotherapy can be considered. Alternatively, investigational drugs or biological agents are often available for trial at children’s cancer centers. Supportive treatments are always available, especially for dying patients, who should never be allowed to feel that treatment is stopping.
There are many types of sarcomas, and any single one occurs very rarely. Treatment varies from one patient to the next and can range from simple surgical excision alone to extensive surgery and aggressive chemotherapy, with or without radiation. In general, staging and treatment are similar to those for rhabdomyosarcoma. Treatment can be somewhat less aggressive for small, completely excised tumors.Extremity, back of abdomen, trunk
Osteogenic Sarcomas
These highly malignant tumors are composed of abnormal cancerous bone cells. They can spread throughout the body, producing new masses, called metastases.
Osteogenic sarcomas occur most commonly during or just after the years of rapid growth, in the teens and early twenties.
Symptoms There is usually swelling and persistent pain in the involved bone, which is most commonly just above or below the knee, in the hip, or in the arm at the shoulder. Any bone may be involved, however. Because of the weakening of the bone by the tumor, there may be a fracture at the cancer site.
Diagnosis and Staging An X-ray may lead to suspicion of an osteogenic sarcoma, but a biopsy is needed for a diagnosis. Determining the extent of disease—staging—is done by looking at the most likely areas of spread with CT, MRI, and bone scans. These areas include the lungs and other bones.
Treatment by Stage
Localized
This stage of the disease is highly treatable and often curable. The surgeon, radiation oncologist, and pediatric oncologist, along with the pathologist and radiologist, should meet at a tumor board to plan the overall approach to therapy.
Standard Treatment Some years ago, it was customary to recommend amputation for bone sarcomas involving the arms or legs. Nowadays, it may be possible to save the extremity (limb salvage) by the use of a combination of several treatment methods, often including a prosthesis, which is surgically inserted to replace the bone that must be removed. Often the first intervention is chemotherapy using drugs such as cisplatin, doxorubicin (Adriamycin), and methotrexate (Amethopterin, Folex) in an attempt to shrink the tumor. Whether a limb-saving surgery or an amputation is performed depends on many factors, including the location of the tumor, the response to chemotherapy, the age of the patient, and the wishes of the patient and family. Further chemotherapy is given after surgery, sometimes with the same drugs used preoperatively.
Five-Year Survival 60 to 70 percent
Metastatic
When the tumor has spread through the blood, the disease is still treatable and occasionally curable.
Standard Treatment The most aggressive chemotherapy approaches are used. More intense chemotherapy, made possible by the use of bone-marrow-stimulating factors and optimum supportive care measures for complications such as infections and bleeding, may improve survival. Best results are achieved when all sites of disease can be surgically removed. Radiation may occasionally be given to sites of metastases, but radiation is not particularly effective.
Five-Year Survival 10 to 20 percent
Recurrent Cancer
When osteogenic sarcomas recur, optimal results are achieved if it is possible to surgically remove all sites of disease. Chemotherapy may or may not be necessary. Consideration for investigational or palliative therapy is very reasonable if the disease is not surgically resectable.
Ewing’s Sarcoma
This is the second most common bone cancer in adolescents and young adults, occurring usually in those between five and twenty years of age. It may also occur in soft tissue (extraosseous Ewing’s sarcoma). A more differentiated or mature form of this tumor can develop in either bone or soft tissue, especially in the chest wall, and this form was previously called a peripheral primitive neuroectodermal tumor (pPNET).
Symptoms The most typical sign of the disease is persistent bone pain in one place, most commonly in an extremity, the pelvis, or a rib.
Diagnosis and Staging Bone X-rays and CT or MRI scans can strongly suggest a diagnosis of Ewing’s sarcoma, but definitive diagnosis depends on a biopsy. Chromosome analysis of tumor tissues is often helpful in establishing the diagnosis.
A bone scan, a bone marrow analysis, a CT scan of the chest, and an MRI scan of the primary site are necessary to determine the extent of the disease.
Treatment by Stage
Localized
The tumor has not spread beyond the site of origin.
Standard Treatment When the tumor is in a bone that can be removed without causing a significant physical handicap, the bone is surgically removed. Unlike treatment for osteogenic sarcomas, major bones are not removed and amputations are not generally recommended because the tumor is sensitive to radiation therapy.
Chemotherapy is usually given before local control (surgery and/or radiation) to shrink the original tumor and treat microscopic spread that does not show up on imaging studies. Combinations of vincristine, doxorubicin (Adriamycin), cyclophosphamide (Cytoxan) and/or ifosfamide, and etoposide are used.
Five-Year Survival 70 to 80 percent
Metastatic
The tumor has spread, usually to the lungs, other bones, and the bone marrow.
Standard Treatment The initial treatment is similar to that for localized disease, but more aggressive chemotherapy and radiation are used. Some patients may even be treated with higher doses of therapy and bone marrow transplant.
Supportive care measures, such as administering bone marrow growth factors, preventing infections, and intensively treating fever, are important parts of the treatment plan.
Five-Year Survival 20 to 45 percent
Recurrent Cancer
This serious complication is even worse if it occurs while the initial treatment is being given. If combination chemotherapy causes the tumor to shrink, consideration should be given to very high dose chemotherapy combined with radiation therapy. This would require a subsequent bone marrow transplant to replace the bone marrow destroyed by these treatments. No reliable figures are yet available to predict the outcome of this approach. Investigational therapy is an alternative, as is palliative treatment.
The Most Important Questions You Can Ask
• What are the details of treatment that will allow my child to receive optimum care?
• Is my child being treated at a medical center that specializes in cancer in children and adolescents?
• What can I do to minimize side effects of chemotherapy or radiation?
• How can I help my child [especially teenagers] cooperate with the treatment program?
• Is a limb-salvage operation or an amputation for osteogenic sarcoma the best procedure and how will each affect quality of life and survival?
• Are further surgical procedures likely if a limb-salvage procedure is done?
• Does my child understand that the disease is not his or her fault and that no one else can catch it?
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