Hypofractionated whole breast radiotherapy in breast conservation for early-stage breast cancer: a systematic review and meta-analysis of randomized trials.

PURPOSE: Breast conservation therapy (BCT) for early-stage breast cancer involves lumpectomy followed by whole breast radiotherapy, which can involve either standard fractionation (SRT) or accelerated fractionation (ART). This systematic review and meta-analysis was performed to determine whether any benefit exists for ART or SRT. MATERIALS AND METHODS: We searched MEDLINE (1966-2014), all seven databases of the Cochrane Library (1968-2014), EMBASE (1974-2014), clinicaltrials.gov, ISRCTN, WHO ICTRP, and meeting abstracts in the Web of Science Core Collection (1900-2014). RCTs comparing SRT to ART among women undergoing BCT with stage T1-T2 and/or N1 breast cancer or carcinoma in situ were included. Follow-up was 30 days for acute toxicity, or three years for disease control and late toxicity. RESULTS: 13 trials with 8189 participants were included. No differences were observed in local failure (n = 7 trials; RR 0.97; 95% CI 0.78-1.19, I 2 = 0%), locoregional failure, (n = 8 trials; RR 0.86; 95% CI 0.63-1.16, I 2 = 0%), or survival (n = 4 trials; RR 1.00; 95% CI 0.85-1.17, I 2 = 0%). ART was associated with significantly less acute toxicity (n = 5 trials; RR 0.36; 95% CI 0.21-0.62, I 2 = 20%), but no difference in late cosmesis (RR 0.95; 95% CI 0.81-1.12, I 2 = 54%). CONCLUSIONS: ART use does not reduce disease control or worsen long-term cosmetic outcome, and may decrease the risk of acute radiation toxicity as compared to SRT.