Radiation Therapy for Ovarian Cancer

Modern radiation therapy for ovarian cancer is given with machines that produce high-energy external radiation beams. These beams penetrate the tissues and deliver radiation deep into the areas where the cancer resides. These modern machines and other state-of-the-art techniques have enabled radiation oncologists to significantly reduce side effects and to minimize the radiation dose to normal tissue.

Simulation

After an initial consultation with a radiation oncologist, the next session is usually a planning session, which is called a "simulation.” Of all of the visits to the radiation oncology facility, the simulation session may actually take the most time.

During simulation, patients lie on a table somewhat similar to that used for a CT scan. The "simulator" machine lets the radiation oncologist see the area to be treated. The room is darkened while the treatment fields are being set, and temporary marks may be made on your skin with magic markers.

The simulation may last anywhere from 15 minutes to an hour or more, depending on the complexity of what is being planned. Once the aspects of the treatment fields are satisfactorily set, x-rays of the treatment fields are taken. The treatment plans and treatment fields resulting from the simulation session are transferred over to the treatment room where the radiation will take place.

A typical course of radiation therapy for ovarian cancer entails daily radiation treatments, Monday through Friday, for three to five weeks. This may vary depending on individual circumstances. The actual treatment with radiation generally lasts no more than a few minutes, during which time the patient is unlikely to feel any discomfort.

Anesthesia is not needed for radiation treatments, and patients generally have few restrictions on activities during radiation therapy. Many patients continue to work during the weeks of treatment. Patients are encouraged to carefully gauge how they feel and not to overexert themselves.

Side Effects and Complications

The majority of patients are able to complete radiation therapy for ovarian cancer without significant difficulty. Side effects and potential complications of radiation therapy are limited to the areas that are receiving treatment with radiation. The chance of a patient experiencing side effects is highly variable. A dose that causes some discomfort in one patient may cause no side effects in other patients.

Radiation therapy to the abdominal/pelvic area may cause diarrhea, abdominal cramping or increased frequency of bowel movements or urination. These symptoms are usually temporary and resolve once the radiation is completed. Occasionally, abdominal cramping may be accompanied by nausea. Some patients have changes in sleep or rest patterns during the time they are receiving radiation therapy and some patients will describe a sense of tiredness and fatigue.

Blood counts can be affected by radiation therapy. In particular, the white blood cell and platelet counts may be decreased. This is dependent on how much bone marrow is in the treatment field and whether the patient has previously received or is currently receiving chemotherapy. These changes in cell counts are usually insignificant and resolve once the radiation is completed. Many radiation therapy institutions make it a policy to check the blood counts at least once during the radiation treatments.

Adjuvant Radiation Therapy

It is important to understand that many patients with ovarian cancer already have small amounts of cancer that have spread into the lymph nodes and cannot be detected with any of the currently available tests. Undetectable areas of cancer are referred to as micrometastases. The presence of micrometastases causes cancer recurrence following treatment with surgery alone.

An effective treatment is needed to cleanse the body of micrometastases in order to improve a patient's duration of survival and the potential for cure. The delivery of cancer treatment following local treatment with surgery is referred to as "adjuvant" therapy and may include chemotherapy, radiation therapy, and/or biologic therapy.

Adjuvant radiation therapy administered after surgery was frequently used before effective chemotherapy was developed. Adjuvant radiation has largely been replaced by adjuvant chemotherapy. However, the combination of chemotherapy and radiation therapy following surgical removal of the cancer may help prevent cancer recurrences.