Radiation Therapy for Childhood Cancer may Have Risk for Further Development of Tumor at CNS
Radiation is everywhere - in soil, water, food, building materials, and even our own bodies. Too much of it can be harmful, but in the right amounts, radiation has many uses. It can be used to make X-rays, create electricity, and even power submarines. And radiation can also be used to help people with cancer.Radiation therapy (say: ray-dee-ay-shun ther-ah-pee) is one form of treatment for kids or adults who have cancer. Both adults and kids can get cancer, but kids don't get it very often. Cancer is a disease that causes normal cells in the body to grow out of control. If left untreated, these cells can grow throughout the body, making the person very sick. Radiation therapy kills cancer cells and keeps them from growing and multiplying. The fewer cancer cells, the better, because then a person can start feeling well again.
Cancer can be treated with radiation therapy alone or in combination with chemotherapy or surgery. Chemotherapy (say: kee-mo-ther-uh-pee) is a treatment that uses medicine to destroy cancer cells. Some people may first have surgery to remove cancer cells or tumors and then have radiation therapy. Each person's treatment depends on the kind of cancer they have.
The immediate side effects of radiation therapy, which occur within the first few hours and days, may include diarrhea, nausea, vomiting and tiredness. Mouth sores also can be a problem due to the combination effect of chemotherapy and radiation. Many children complain of a dryness of the mouth, sore throat and thickened saliva. Starting several days after radiation therapy, hair loss, sunburning and dryness of the skin may be experienced. Much rarer side effects include swelling (like mumps) of the glands in the cheeks and fever. Radiation therapy also destroys the cells of the bone marrow and, most importantly, cancer cells.
Recently,according to new data from the Childhood Cancer Survivor Study found that in survivors of childhood cancer, exposure to radiation therapy, especially before 5 years of age, is "the most important" risk factor for the development of a new primary tumor of the central nervous system (CNS).
he most common CNS tumors in these children are gliomas and meningiomas, which are primarily located in the brain but can occur elsewhere.
"A small fraction of children may develop new cancers later in life as a result of these exposures," Dr. Joseph P. Neglia of the University of Minnesota Medical School and Cancer Center in Minneapolis told Reuters Health. "A very small fraction (less than 1 percent) will develop brain tumors."
The higher risk of second (CNS tumors) in children who undergo radiation at a very young age may reflect a greater susceptibility of the developing brain, he and his colleagues suggest in the Journal of the National Cancer Institute.
In a study of 14,361 patients who survived for 5 years after their childhood cancer, 116 developed subsequent primary CNS tumors. Forty gliomas appeared about 9 years after the original diagnosis; 66 meningiomas occurred at about 17 years after the initial cancer.
Treatment with radiation was associated with a greater than 6-fold increased risk of subsequent glioma and a nearly 10-fold increased risk of subsequent meningioma.
"Risk of a subsequent CNS tumor increased as the dose of radiation used for treatment of the original cancer increased," Dr. Neglia told Reuters Health. The children who were youngest when they underwent radiation had the highest risk of developing another CNS cancer, he added.
This study makes clear the strong impact of radiation therapy on the occurrence of subsequent tumors of the CNS. Despite the risks, however, the use of radiation "is justified in these settings," the researchers note, "because 60 percent of deaths among survivors of childhood cancer who are 5 or more years results from recurrence or progression of their original disease."
They conclude that "prolonged follow-up of all childhood cancer survivors, particularly those exposed to radiation is crucial to the early detection of these tumors and should be considered part of the effective therapy of the primary disease."
"It is also important," Neglia added, "for all pediatric cancer survivors to know their medical history, the therapy they received, and the recommendations for their follow-up."
"Many centers have Long-Term Survivor Clinics specifically dedicated to the needs of these survivors. While the most malignant tumors occur early, other tumors (meningiomas) continued to occur throughout follow-up. Screening for a secondary tumor of the CNS could be considered on a case-by-case basis by a patient and their physician."
The primary goal when treating children with cancer is to cure them; this takes priority over all other aspects of care. However, there are many medications and therapies that can make children more comfortable while undergoing treatment for cancer.