Gale Encyclopedia of Childhood and Adolescence

Cancer is a family of diseases in which cells replicate at an extremely rapid pace. A cancerous, or malignant, tumor begins its growth at a primary site, damaging surrounding tissue and interfering with normal organ function. Eventually, some of the cancerous cells may migrate from the primary tumor to other parts of the body via the bloodstream and form secondary tumors. The specific causes of most forms of cancer are unknown, but researchers have uncovered many probable factors that contribute to the development of the disease, including certain chemicals and forms of radiation, cigarette smoking, diet, and, in some cases, genetic predisposition. Although most cancers occur in adults, cancer is still responsible for more deaths in children than any other disease in the United States, where it is the second leading cause of death--after accidents--in children under the age of 15. Between 7,000 and 8,000 new cases of childhood cancer are diagnosed in the U.S. every year. Like the cancer rate among the adult population, the incidence of cancer in children, especially acute lymphocytic leukemia and brain cancer, is on the rise. However, scientific advances in diagnosis and treatment have dramatically improved short- and long-term survival rates for many childhood cancers.

Pediatric oncologists specialize in the treatment of children with cancer. Childhood cancers are treated with the same three major techniques used for treating cancer in adults: chemotherapy, radiation, and surgery. In chemotherapy, medication is administered orally or intravenously to kill cancer cells, or to stop or retard their growth. Usually a combination of different drugs is used for maximum effectiveness. Chemotherapy agents are powerful drugs that cause unpleasant and sometimes serious side effects, including nausea, hair loss, mouth sores, bleeding, and decreased immune function.

In radiation therapy, high doses of radiation are aimed at the affected area, killing cancer cells. This therapy brings many dangers to the patient. Radiation can kill cells or turn healthy cells into new cancer cells. Whole-body radiation, used to treat cancer that has spread, destroys the body's bone marrow. A matching donor, usually a close relative, must then be found to give marrow for a transplant procedure. Side effects of radiation include fever, irritability, hair loss, headaches, nausea, and appetite loss, in addition to skin irritations at the site where the x rays are aimed. New treatment approaches being developed for children can reduce the side effects of radiation. These include hyperfractionation, which reduces the required dose of radiation, and tailored radiotherapy, which narrows the radiation to only a portion of the affected area. Surgery is the treatment of choice for localized cancers that are detected before they have spread. However, some cancers are more treatable by surgery than others, depending on the accessibility of the tumor. Surgery is often used in conjunction with radiation and/or chemotherapy to prevent a relapse, because if even a single cancer cell is left after the operation, it can lead to renewed abnormal growth and the recurrence of the tumor.

Types of childhood cancers

The most common childhood cancers are leukemia , brain cancer, and lymphoma. Leukemia, which accounts for a third of the cancers diagnosed in children every year, affects the tissues that produce blood cells, causing a proliferation of abnormal white cells in the bone marrow. These crowd out the normal cells, interfering with blood clotting, leading to anemia, and making the child vulnerable to severe infections. Almost all cases of childhood leukemia, 97%, are acute and progress rapidly. Acute lymphocytic leukemia (ALL) is the most widespread type, accounting for 80-85% of cases in children. Leukemia usually strikes children between the ages of three and five. Symptoms include fatigue, pallor, fever, infections, abnormal bruising, bleeding gums, nosebleeds, and limping. The most effective treatment is chemotherapy to kill the abnormal white blood cells, accompanied initially by blood transfusions and antibiotics. Bone marrow transplants are becoming an increasingly frequent treatment method for this disease. After the diseased marrow is destroyed by radiation or chemotherapy, marrow cells from a compatible donor, usually a sibling, are transplanted into the patient. Treatment advances raised the survival rate for childhood leukemia from 4% in the 1960s to 70% by the 1980s.

Brain tumors are the second most common childhood cancer. Nearly half belong to one particular type, called an astrocytoma. If the tumor is in an operable location, the prognosis for 10-year survival is 80%. Hodgkin's disease and other cancers of the lymph system, or lymphomas, are also among the most frequent childhood cancers. Symptoms of lymphoma include fever, night sweats, swollen, tender lymph nodes, jaundice (yellowish skin and eyes), decreased appetite, and, in the case of Hodgkin's lymphoma, widespread itching. Current survival rates for lymphomas are excellent. With radiation and chemotherapy, the five-year survival rate for Hodgkin's disease is 90%, and the 10-year survival rate is 80%. Non-Hodgkin's lymphoma has a two-year survival rate (with treatment) of 70%, after which relapse is infrequent. With early detection and treatment, the survival rate for non-Hodgkin's lymphoma is as high as 90%.

Children can also develop various types of bone cancer. Two of the most common are osteosarcoma and Ewing's sarcoma. Adolescents, particularly adolescent boys, are especially prone to bone cancer, which tends to develop during growth spurts. The initial symptoms of a bone tumor--pain and swelling--may cause it to be mistaken for a bruise. If the cancer is allowed to progress untreated, it will eventually interfere with use of the affected part of the body--usually an arm or leg--and can make it sensitive to fractures. Although bone cancer is most commonly seen in the limbs, it can also occur in other locations, such as knees, hips, or shoulders. Bone cancer can develop in more than one location simultaneously or can spread from one part of the body to another. Bone tumors are generally diagnosed by a combination of x ray and biopsy , in which a small amount of the tumor is removed for laboratory analysis. More sophisticated radiological procedures, such as a bone scan or a CAT scan (computed tomography, or CT), can aid in making a more detailed assessment and deciding on a course of treatment.

Surgery, followed by chemotherapy, is the treatment of choice for osteosarcoma. Usually the affected limb is amputated, although in some cases it is possible to remove only part of the limb, followed by reconstruction through a bone transplant or graft. Ewing's sarcoma is treated with radiation and chemotherapy but not surgery. Due to treatment advances, the prognosis for bone cancer--once considered an almost uniformly fatal illness--has improved dramatically in recent decades. The five-year collective survival rate for bone cancer is now 80%. As many as 50% of Ewing's sarcoma patients are likely to be long-term survivors of the disease. Similarly, the survival rate for osteosarcoma has risen to 50% from only 20% in the 1960s.

Another type of childhood cancer is Wilms' tumor, also known as nephroblastoma. Wilms' tumor is a kidney tumor originating from embryonal kidney cells that is most frequent in children under the age of five. A genetic component has been found in this disease, which is also associated with congenital urinary tract and genital deformities, such as undescended testicles. In most cases, the tumor is first detected as a lump in the abdomen or side. Other symptoms may include swelling, abdominal pain, appetite reduction, weight loss, fever, and urine in the blood. Without the standard treatment of surgery and chemotherapy, the tumor can spread to other organs, including the lungs and liver. Even if the tumor has spread, necessitating the removal of additional tissue besides the affected kidney, recovery from surgery is usually rapid. However, the child's health must be monitored regularly following treatment and recovery, as the tumor may recur, especially in the lungs. Since the 1960s the survival rate for Wilms' tumor has risen from 33% to over 80%.

Emotional and psychological health

In addition to medical treatment, it is important for children with cancer and their families to receive adequate emotional support, which can come from friends, extended family, mental health professionals, support groups, or clergy. In addition to conventional counseling, resources such as play therapy and art therapy can help children cope with emotions such as fear and depression. Support groups for children with cancer can also be an important source of reassurance and comfort. In addition, family members of the patient can benefit from individual or group counseling. The serious illness of a child can place a heavy strain on a couple's marriage, and counseling can help parents work through their conflicts and remain healthy emotionally. Childhood cancer is also stressful for siblings, who may feel guilty, depressed, or resentful of the extra parental attention devoted to the brother or sister who is ill. They can also benefit from some form of extra emotional support.

Education is another area of special concern for children with cancer. It is helpful for them to maintain as much of a normal routine as they can, and there are resources available to help them continue their schooling in spite of the interruptions imposed by possibly lengthy hospital stays. Private tutoring is a common option. The Minnesota branch of the American Cancer Society has developed a school reentry program to help make a child's return to school easier following cancer treatment. A pediatric oncology nurse visits the child's school in advance to educate both the school staff and the child's classmates about cancer and its treatment. Special age-appropriate materials, such as coloring books and videos, have been developed for use in the program. These visits can help allay other children's fears about the disease (for example, the idea that it may be contagious) and teachers' anxieties about how to treat a student with cancer.

Although there is still too little certainty about the causes of childhood cancers to make them preventable, there are ways to reduce a child's lifetime chances of developing cancer, based on proven medical findings about factors that contribute to the disease. The most important risk factor is second-hand cigarette smoke. The dangers of passive smoking have been known for years, and there is research establishing a strong link between exposure to smoking during childhood and adolescence and lung cancer in nonsmoking adults. Another area of concern is exposure to toxic substances in and around the home, especially insecticides and weed-killers. Use of household insecticides while a woman is pregnant has been found to nearly quadruple an unborn child's risk of leukemia. Another way to avoid pesticides and herbicides in the home is to eat organically grown fruits and vegetables.

Exposure to radiation in high doses has also been associated with cancer. Radon, a naturally occurring radioactive gas, has been linked to lung cancer by the Environmental Protection Agency (EPA). It is generally recommended that families check the radon levels in their homes against the EPA guidelines for acceptable levels of the gas and take measures to improve sealing and ventilation if the levels are too high.

Another type of radiation that has been linked to cancer is the ultraviolet radiation of the sun, which is the primary cause of skin cancer. Children's skin has less of the pigment melanin than that of adults, making them more sensitive to the sun's rays. A single severe sunburn can increase a child's risk of developing a malignant melanoma later in life, a condition that can be fatal if untreated. In addition, frequent exposure to the sun, even without burning, can increase the chances of developing other types of skin cancer. It is recommended that infants be shaded from strong sunlight by hats, bonnets, stroller covers, and other kinds of protective covering. Active older children can be protected by a sunscreen lotion or cream with a sun protection factor (SPF) of at least 15, applied on all areas exposed to the sun. Direct exposure to the sun can also be limited during the hours between 10 a.m. and 3 p.m. . when ultraviolet rays are strongest.

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Another risk factor for developing cancer is an unhealthy diet. Certain kinds of cancer are associated with a high level of fat consumption. Fat should only account for 20-25% of the calories consumed daily by those two years of age and older. It is also recommended that both children and adults eat at least five servings of fruits and/or vegetables daily.

Further Reading

For Your Information

Books

• Froemer, Margot Joan. Surviving Childhood Cancer: A Guide for Families. Washington, DC: American Psychiatric Press, Inc., 1995.
• Gaes, Geralyn, Craig Gaes, and Philip Bashe. You Don't Have to Die: A Family's Guide to Surviving Childhood Cancer. New York: Villard Books, 1992.
• Hyde, Margaret O., and Lawrence E. Hyde. Cancer in the Young: A Sense of Hope. Philadelphia: Westminster Press, 1985.
• National Cancer Institute. Tips for Teenagers with Cancer. Bethesda, MD: U.S. Department of Health and Human Services, 1987.
• Trillin, Alice. Dear Bruno. New York: The New Press, 1996.

Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.