EF, Lee WR.

Source

Department of Radiation Oncology, Duke University School of Medicine, Durham, NC 27710, USA.

Abstract

In ideal circumstances, the fractionation schedule of radiotherapy should match the fractionation sensitivity of the tumor relative to the nearby normal tissues. A number of recent publications have suggested that the alpha-beta ratio (alpha/beta) for prostate is low, in the range of 1 to 3 Gy. If alpha/beta is truly low, then hypofractionated schedules using fewer, larger fractions should improve the therapeutic ratio. This critical review examines the clinical experience with hypofractionation. Several prospective trials indicate that toxicity is limited with sophisticated dose delivery and compact clinical target volume to planning target volume margins, but the single-arm nature of these trials precludes definitive statements on efficacy. Several large randomized trials comparing conventional fractionation to hypofractionation are ongoing and are described. Until these trials are completed and the results submitted for rigorous peer review, the notion that alpha/beta for prostate cancer is low remains an unconfirmed hypothesis.

Hypofractionation for clinically localized prostate cancer

2013 Jul;23(3):191-7. doi: 10.1016/j.semradonc.2013.01.005.

Cabrera AR, Lee WR.

Source

Department of Radiation Oncology, Duke Cancer Institute, Durham, NC. Electronic address: alvin.cabrera@duke.edu.

Abstract

This manuscript reviews the clinical evidence for hypofractionation in prostate cancer, focusing on data from prospective trials. For the purposes of this manuscript, we categorize hypofractionation as moderate (2.4-4 Gy per fraction) or extreme (6.5-10 Gy per fraction). Five randomized controlled trials have evaluated moderate hypofractionation in >1500 men, with most followed for >4-5 years. The results of these randomized trials are inconsistent. No randomized trials or other rigorous comparisons of extreme hypofractionation with conventional fractionation have been reported. Prospective single-arm studies of extreme hypofractionation appear favorable, but small sample sizes preclude precise estimates of efficacy and short follow-up prevents complication estimates beyond 3-5 years. Over the next several years, the results of 3 large noninferiority trials of moderate hypofractionation and 2 randomized trials of extreme hypofractionation should help clarify the role of hypofractionation in prostate cancer therapy.