Hypofractionated, Dose-Escalated Radiation Versus Conventionally Fractionated Radiation for Localized Prostate Cancer: Long-Term Update of a Phase III, Prospective, Randomized Controlled Trial.

Abstract

The MD Anderson dose-escalated, hypofractionated prostate radiation study was a phase III randomized trial comparing conventionally fractionated intensity-modulated radiation therapy (CIMRT, 75.6 Gy in 1.8-Gy fractions) with dose-escalated, hypofractionated intensity-modulated radiation (HIMRT, 72 Gy in 2.4-Gy fractions) in patients with localized prostate cancer, predominantly low-risk and intermediate-risk disease. The initial publication highlighted statistically fewer treatment failures in the HIMRT arm. We present long-term updated 13-year outcomes to determine whether cancer control benefit was maintained and to evaluate distant metastases post hoc. With a median follow-up of 13.2 years (IQR, 8.8-15.9 years), treatment failure occurred less frequently in men undergoing HIMRT (n = 13) compared with those undergoing CIMRT (n = 22), although the difference no longer meets statistical significance (P = .08). Distant metastases were rare, and no statistically significant difference was noted (P = .2). There remained no statistically significant difference in late GI 2+ (10-year 10% HIMRT v 4% CIMRT, P = .09) or genitourinary grade 2+ toxicity (10-year 26% v 23%, P = .5).