Understand Childhood Cancers and Blood Disorders
Radiation therapy is a useful tool in the treatment of many childhood malignancies. It is often used as part of a program of cancer treatment in combination with other treatments which might include surgery and chemotherapy, but it can also be used alone. Radiation therapy is particularly helpful in the management of selected patients with brain tumors, Wilm's tumor and some sarcomas. It may also be used for some patients with leukemia or other conditions. Radiotherapy uses ionizing radiation to kill cancer cells and shrink tumors. This high energy radiation usually comes from x-rays or gamma rays but may also be delivered by particle beam or proton beam therapy. These therapies can penetrate into tissues to stop tumor cell growth and destroy cancer cells. Most pediatric patients who receive radiotherapy will get external radiation which is delivered by a machine adjacent to the patient. Radiation therapy is usually given to selected patients with malignant diseases who are at least three years of age; it is uncommon for it to be given before this age.
Radiation therapy begins with referral from a pediatric oncologist to a radiotherapist experienced in the treatment of children. This physician evaluates the patient's clinical information, reviews imaging studies and pathology reports and then proceeds with treatment planning. This planning process encompasses the decision of whether or not the tumor is likely to respond to radiation therapy and which type is best. Next, the radiotherapist decides how much radiation to administer and over what time period. Treatment is always designed to spare as much normal tissue as possible. Occasionally, a patient is referred to a specialized center for a type of radiation treatment not available in the New York metropolitan area.
Most patients who are referred for radiation therapy are treated with a curative intent. The goal of this type of radiation treatment is the elimination of the entire tumor by the complete destruction of all cancer cells. In some patients with acute leukemias, the most common type of pediatic cancer, it may be necessary to administer radiation to areas that do not have evidence of cancer but are at very high risk for tumor spread. This is done to prevent cancer cells from growing in the area receiving the radiation. This prophylactic radiation therapy is used only when clinical research has demonstrated that clear benefit to the patient will likely result. In some difficult cases, the aim of treatment will be to shrink a tumor in order to relieve pain or other symptoms - this latter type of treatment is termed palliative therapy.
After discussing the benefits and potential adverse effects with the patient and the family, the next step is simulating the radiation treatment. This process involves special imaging and careful positioning of the patient in order to develop a plan to deliver radiation to the exact tissues which require treatment. Special marks placed on the patient's skin serve as a reference point which guide the radiation treatment team so that the daily doses of radiation are delivered on a consistent basis to the proper sites of disease.
Following the simulation, treatment begins. Younger patients who require radiotherapy are sedated by an anesthesiologist who administers sedative drugs to the patient while monitoring the patient's airway and vital signs. The treatment itself requires only a few minutes and does not cause pain. Treatment courses are typically given on weekdays and may last from 6 to 45 days of total treatment. Splitting the radiation treatments into daily doses allows the patient to benefit from the treatments with the fewest adverse effects.
Adverse effects of radiation depend upon the site or sites that require treatment and how much treatment is given. Both the pediatric oncologist and the radiotherapist are able to monitor the patient for adverse effects of the radiation therapy and can prescribe treatments to minimize discomfort.