Use of Individual Fraction Size Data from 3756 Patients to Directly Determine the α/β Ratio of Prostate Cancer

Abstract

Purpose: To examine the effect of fraction size and total dose of radiation on recurrence of localized prostate cancer. Methods and Materials: A total of 3756 patients treated with radiation monotherapy at three institutions were analyzed, including 185 high-dose-rate brachytherapy (HDRB) boost patients. The 5th to 95th centiles of external beam radiotherapy (EBRT) fraction sizes and doses were 1.8 to 2.86 Gy, and 57.4 to 77.4 Gy, respectively, and HDRB fractional doses were between 5.5 and 12 Gy, totaling 147 unique fractionation schedules. Failure was defined by one biochemical (nadir + 2 ng/ml) and two advanced disease endpoints. The α/β ratios were estimated via a proportional hazards mo..