Effect of Hypofractionation on Prostate Cancer Radiotherapy

Abstract

Context: Prior research over the past few decades has shown that the hypofractionated external beam radiation therapy could be a valuable method with an outstanding potential to treat the prostate cancer. The alpha-beta ratio (alpha/beta) is an indication of the fractionation sensitivity of a particular cell type. Values of alpha/beta >= 10 Gy are responsible for early-responding normal tissues and most tumors, while values of alpha/beta < 5 Gy are for late-responding normal tissues. The alpha/beta ratio could be raised by either a local tumor control increase or a decrease of normal tissue late effects through the application of an unconventional fractionation schedules. Evidence Acquisition: This review article aimed to investigation the details of radiobiological and clinical trials which are reported to highlight the characteristics of hypofractionation for the prostate cancer treatment based on the investigation of clinical results from hypofractionated treatments. Results: With the sufficient radiobiological and physiological research studies, it may be claimed that if alpha/beta value for prostate cancer is less than the adjacent surrounding organs at risk and by applying fewer and larger fractions; a better therapeutic ratio can be achieved for the patient. Conclusions: Radiobiological modeling can play a major role in the design of new protocols. Also, one should be aware that in modeling the hypofractionated treatment, normal tissue iso-effects are significantly important and some assumptions needed to be made regarding alpha/beta values for the critical normal tissue complication endpoint.