External beam irradiation for localized prostate cancer--the promise of hypofractionation

Within the field of radiation oncology in the last 10 years, there have been two major thematic advances in the understanding and treatment of prostate cancer. Computerized treatment planning and high precision delivery techniques have already revolutionized the treatment of this disease. Three randomized studies have reported improved biochemical disease-free survival rates in patients from low- to high-risk disease with higher radiation doses. When given conformally, the higher doses do not appear to increase severe toxicity. The second important discovery was that prostate cancer reacts differently than other tumors to radiation whereby higher doses of radiation per day ("hypofractionated radiation") seem to be more effective in killing prostate cancer cells. A meta-summary of four reports summarizing 21 studies presented herein produced an alpha/beta ratio of 1.3 Gy. The early experience of two hypofractionated trials in intermediate- and high-risk prostate cancer where the equivalent of > 80 Gy (in 2 Gy per day fractions) delivered in 5-6 weeks is reported. In summary, hypofractionated radiation coupled with high-precision techniques may allow for better prostate cancer control rates, shorter treatment times and less toxicity.