Prospective Randomized Trial of Prone Accelerated Intensity Modulated Breast Radiotherapy with a Daily versus Weekly Boost to the Tumor Bed
Mené sur 400 patientes atteintes d'un cancer du sein de stade 0 à II et ayant subi une mastectomie segmentaire (durée médiane de suivi : 45 mois), cet essai de non infériorité évalue, en fonction de la fréquence d'administration (quotidienne ou hebdomadaire), la toxicité aiguë d'une dose de rayonnement additionnel du lit tumoral dans le cadre d'une radiothérapie accélérée avec modulation d'intensité et positionnement de la patiente en décubitus ventral
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 in the prone position. Methods and Materials : From 2009-2012, 400 stage 0-II breast cancer patients who had undergone segmental mastectomy participated in an IRB-approved trial testing prone breast radiotherapy to 40.5 Gy/15 fractions to the whole breast, five days a week after randomization to a concomitant daily boost to the tumor bed of 0.5 Gy, or a weekly boost of 2 Gy, on Friday. This non-inferiority trial tested the primary hypothesis that a weekly boost produced no more acute toxicity than a daily boost. Recurrence Free Survival (RFS) was estimated for both treatment arms using the Kaplan-Meier method; the relative risk of recurrence or death was estimated and the two arms were compared with the log-rank test. Results : At a median follow-up of 45 months, there were no deaths related to breast cancer. The weekly boost regimen produced no more grade ≥ 2 acute toxicity than the daily boost regimen (8.1% vs 10.4%; non-inferiority Z = -2.52; p = 0.006). There was no statistical difference in cumulative incidences of long term fibrosis or telangiectasia ≥2 between the two arms (log-rank p=0.923). There were 2 local and 2 distant recurrences in the daily arm. There were 3 local and 1 distant recurrences in the weekly arm, with no difference in 4-year RFS between the two arms (98% in both arms). Conclusions : A tumor bed boost delivered either daily or weekly is similarly tolerated during accelerated prone breast radiotherapy, with excellent control of disease and comparable cosmetic results.