Stereotactic Body Radiation Therapy
An Important Advance in Cancer Treatment
Joseph M. Pepek, MD
Radiation therapy, which is part of cancer treatment for about 60% of patients, is used for curative treatments of early-stage cancers of the breast, lung, skin, head and neck, gastrointestinal tract, cervix and uterus, prostate and other areas of the body.
The amount and type of radiation needed depends on several factors: the stage of the cancer, the size and location of the tumor, the health of the patient and the method used to deliver treatment.
Radiation is an effective treatment tool against cancer, but it has a reputation for damaging healthy tissue and causing unpleasant side effects. Sophisticated new methods for delivering radiation therapy have greatly improved the ability to deliver more accurate, high dose radiation to tumor cells while minimizing damage to adjacent normal tissues.
One particular innovation is stereotactic body radiation therapy (SBRT), also known as stereotactic ablative body radiotherapy (SABR). While conventional radiation can damage healthy tissue surrounding a tumor, SBRT delivers very high doses of radiation in a more precise manner. SBRT can minimize damage to healthy tissue, decrease side effects, and allow patients to receive fewer treatments unlike traditional methods.
Radiation oncologists are better able to deliver precise high dose radiation treatments over shorter periods of time while minimizing radiation to normal healthy organs because the ability to image and track the tumor has improved. Radiation oncologists can now plan SBRT treatments using a computed tomography (CT) scan that provides a “four-dimensional” view of a tumor. This type of scan—which creates a "movie" of a tumor during the patient’s respiratory cycle—enables radiation oncologists to know the location of the tumor during all phases of breathing. This method can improve treatment accuracy by taking into account the variability of both organ and tumor motion.
An SBRT treatment course is usually completed in only 1-5 treatments. Each treatment takes approximately 30-60 minutes and all are performed as outpatient visits.
Since the amount of normal tissue affected by SBRT is usually small, the patient's side effects are minimal as well. For example, after an SBRT procedure for early-stage lung cancer, most patients will experience some degree of fatigue. Side effects such as shortness of breath, pain with swallowing or eating, or chest wall pain, are very rare. The radiation oncology team, which includes physicians, nurses, physicists, dosimetrists and radiation therapists, coordinate and plan the treatment and identify and manage potential side effects during and after a patient’s treatment course.
SBRT is one example of how radiation therapy has improved in terms of precision, effectiveness and outcomes for patients. SBRT can achieve local tumor control rates of approximately 90% for patients with small lung cancers. SBRT is an exciting new area of treatment for appropriately selected patients with: 1) early stage lung cancer who are not surgical candidates or refuse surgery, 2) brain and spine tumors, 3) primary liver cancer, 4) pancreatic cancer, 5) prostate cancer and 6) limited liver and bone metastases. Patients should consult with a radiation oncologist to discuss whether they are candidates for SBRT.