Radiation Therapy to Treat Hodgkin's Disease
Radiotherapy - otherwise known as radiation therapy - continues to be the primary treatment for early Hodgkin's disease (HD) and it is used as an adjuvant (helpful) treatment for people with more advanced forms of HD. With new improvements in chemotherapy, radiotherapy has been modified or even eliminated for some types of lymphoma. The exceptions are early-stage low-grade lymphomas, which often can be treated by radiotherapy alone, as well as lymphomas of certain organs, such as the eye.
Radiation Delivery Methods
Radiotherapy uses high-energy, ionizing radiation (e.g., gamma rays) to kill cancer cells. Radiotherapy can be delivered in many ways: (1) by a radiotherapy device, which is used outside of the body, "external beam radiation," in a manner similar to that of an x-ray machine; (2) by injection of a short-lived radioactive chemical such as radioactive phosphorus (32P) into the body; or (3) implantation (surgical placement) of radioactive material in or near a tumor, called "implant radiation."
External beam radiation often is applied to the mantle field - the area including the neck, chest, and underarm lymph nodes - for cases of high-neck or upper torso disease. For disease below the diaphragm, the pelvic lymph nodes and spleen may be targeted. Radiotherapy must reach all cancer cells within the radiation field to be effective. Abdominal organs like the ovaries, liver, kidneys, and small bowel may not be able to withstand the doses of radiation required to destroy all cancerous tissue, and they may need to be shielded during radiotherapy. The ovaries, in particular, actually may be moved surgically ("oophoropexy") to allow their shielding with a full-thickness block. This helps to maintain menstrual function and fertility in many women.
Total nodal irradiation, otherwise known as total lymphoid radiation (TLI), involves the irradiation of all lymphatic tissues within the upper and lower body. This approach may be used for individuals with widespread, late-stage disease, but it is not recommended for patients with early-stage, slow-growing lymphomas.
Total body irradiation (TBI) often is used to prepare patients for a treatment plan of high-dose chemotherapy with stem cell transplantation. Such radiation therapy creates space in the bone marrow for transplanted cells to expand, suppresses immune system rejection of the graft, and helps to eliminate any remaining cancer cells.
Radiation Therapy & Children
The treatment of children with radiotherapy can prevent the normal growth and development of bones, muscles, and other tissues. Therefore, most cancer specialists avoid radiotherapy or use the lowest possible doses of radiation when caring for children with lymphoma.
Side Effects of Radiation Therapy
Physicians carefully calculate the dose and the exact placement of the radiation required to pinpoint and destroy lymphomas. Yet, in spite of these determinations, side effects still occur. Because cancer cells usually multiply faster than most bodily tissues, they are especially affected by radiation, which prevents cell division and the formation of DNA (deoxyribonucleic acid; human genetic material). The specific side effects of mantle field irradiation are:
- radiation pneumonitis - lung inflammation that is characterized by a mild, nonproductive cough, low-grade fever, and difficult breathing with exertion;
- pericarditis - inflammation of covering of the heart;
- thyroid abnormalities;
- Lhermette's syndrome - a mild form of radiation myelitis (spinal cord inflammation), which can cause an "electric shock" sensation down the backs of the legs when the neck is bent;
- second cancers (especially acute leukemia) that arise many years after treatment.
The bodily tissues that divide rapidly—such as the lining of the digestive tract, hair, and skin—are particularly vulnerable to radiotherapy. After mantle irradiation, the patient may experience mouth dryness and inflammation of the pharynx (throat). If the stomach and/or intestines have been irradiated, the individual may have nausea, vomiting, diarrhea, inflammation of the peritoneum (tissue that lines the abdominal cavity), formation of abdominal adhesions (fibrous bands), obstruction of the small bowel, and a lowered blood counts. Other side effects of external beam radiation are skin irritation, edema (swelling), and skin darkening at the treatment site.