Prospective Randomized Trial of Prone Accelerated Intensity Modulated Breast Radiation Therapy With a Daily Versus Weekly Boost to the Tumor Bed.

Overview

abstract

PURPOSE: To report the results of a prospective randomized trial comparing a daily versus weekly boost to the tumor cavity during the course of accelerated radiation to the breast with patients in the prone position. METHODS AND MATERIALS: From 2009 to 2012, 400 patients with stage 0 to II breast cancer who had undergone segmental mastectomy participated in an institutional review board-approved trial testing prone breast radiation therapy to 40.5 Gy in 15 fractions 5 d/wk to the whole breast, after randomization to a concomitant daily boost to the tumor bed of 0.5 Gy, or a weekly boost of 2 Gy, on Friday. The present noninferiority trial tested the primary hypothesis that a weekly boost produced no more acute toxicity than did a daily boost. The recurrence-free survival was estimated for both treatment arms using the Kaplan-Meier method; the relative risk of recurrence or death was estimated, and the 2 arms were compared using the log-rank test. RESULTS: At a median follow-up period of 45 months, no deaths related to breast cancer had occurred. The weekly boost regimen produced no more grade ≥2 acute toxicity than did the daily boost regimen (8.1% vs 10.4%; noninferiority Z = -2.52; P=.006). No statistically significant difference was found in the cumulative incidence of long-term fibrosis or telangiectasia of grade ≥2 between the 2 arms (log-rank P=.923). Two local and two distant recurrences developed in the daily treatment arm and three local and one distant developed in the weekly arm. The 4-year recurrence-free survival rate was not different between the 2 treatment arms (98% for both arms). CONCLUSIONS: A tumor bed boost delivered either daily or weekly was tolerated similarly during accelerated prone breast radiation therapy, with excellent control of disease and comparable cosmetic results.