Q: Why is my prostate radiation course eight weeks? Can you treat my prostate cancer over a shorter course?
A: Radiation therapy for prostate cancer has significantly evolved over the last 20 to 30 years. Historically, definitive radiation therapy for prostate cancer used radiation doses of up to 70 Gray (Gy). Recent advances in radiation technique, including the widespread adoption of intensity-modulated radiation therapy and image-guided radiation therapy, has made it possible to give larger doses over a shorter period with minimal toxicity. Multiple randomized trials have demonstrated that increasing the radiation dose to the prostate results in improved local control (the cancer is confined rather than spreading) and freedom from disease recurrence. As a result, currently, the standard radiation therapy for localized prostate cancer consists of delivering a total of 76 to 80 Gy over seven to eight weeks. In order to minimize potential toxicity, radiation doses are limited to 1.8 to 2 Gy daily.
Radiobiological laboratory studies have demonstrated that due to the unique nature of prostate cancer, it may be particularly sensitive to higher radiation doses and a larger radiation dose per fraction. Short course, or hypofractionated, radiation therapy delivers doses greater than 2 Gy per day with the obvious potential advantages of reduced treatment cost, greater patient convenience, and a theoretical improvement in the therapeutic ratio for prostate cancer. There has been increasing evidence that hypofractionated radiation therapy can result in similar treatment outcomes in men with clinically localized prostate cancer. Further long-term follow-up is needed to confirm that hypofractionated radiation can be delivered safely and effectively vs. conventionally fractionated radiation.
- Eric M. Horwitz, M.D., chairman of the Department of Radiation Oncology at Fox Chase Cancer Center; and Talha Shaikh, M.D., radiation oncology resident at Fox Chase.