Abstract P3-12-15: Effect of hypofractionated radiotherapy for the treatment of early stage breast cancer: Meta-analysis on efficacy and safety
Authors: Nazário ACP , Andrade TRdM , Segreto HRC , Segreto RA , Fonseca MCM 
Published: May 2016

Abstract
Objectives: To evaluate the short and long term effect of hypofractionated radiotherapy on efficacy and safety in women with early stage breast cancer that underwent breast-conserving surgery. Methods: We searched in Embase, Medline, Cochrane Library, and Lilacs for randomized controlled trials comparing conventional unconventional fractioning. Two reviewers obtained data independently and disagreements were solved by consensus. We measured the effect of fractioning within 5 years and after 5 years of treatment by means of the relative risk (RR) obtained from a meta-analytic random effects model comparing unconventional and conventional fractioning in relation to local, loco-regional and distant recurrence, mortality, disease-free survival (number of patients with disease-related events), ischemic heart disease, rib fractures and lung fibrosis. Results: We included five medium/ high quality studies totalizing 7.802 women. Unconventional fractioning does not change within 5 years and after 5 years, respectively: (1) local recurrence RR 0.90 (95% CI 0.68 to 1.18; P = 0.44) and RR 0.98 (95% CI 0.83 to 1.17; P = 0.86); (2) locoregional recurrence RR 0.99 (95% CI 0.71 to 1.36; P = 0.84) and RR 0.97 (95% CI 0.77 to 1.23; P = 0, 79); (3) distant recurrence (RR) 1.04 (95% CI 0.73 to 1.46; P = 0.84) and RR 1.02 (95% CI 0.79 to 1.32; P = 0 , 88); (4) mortality RR 0.89 (95% CI 0.77 to 1.05; P = 0.16) and RR 0.96 (IC 95% from 0.89 to 1.08; P = 0.48); (5) disease-free survival RR 0.96 (95% CI 0.78 to 1.18; P = 0.69) and RR 0.96 (95% CI 0.84 to 1.09, P = 0, 49); (6) cardiac ischemia (radiotherapy in both breasts) RR 0.73 (95% CI 0.34 to 1.57; P = 0.42) and RR 0.61 (95% CI 0.33 to 1.15; P = 0.13); (7) cardiac ischemia (radiotherapy only in the left breast) RR de 0.84 (95% CI; 0.21 to 3,.7; P= 0.80) and RR de 0.72 (95% CI, 0.28 to 1.86; P= 0.49); (8) rib fractures RR 1.02 (95% CI 0.25 to 4.20; P = 0.98) and RR 1.08 (95% CI 0.26 to 4.53; P = 0, 91); (9) pulmonary fibrosis RR 2.42 (95% CI 0.50 to 11.71, P = 0.27) and RR 3.16 (95% CI 0.89 to 11.21, P = 0.07). In a subanalysis, removing the fractioning not recommended by ASTRO, unconventional fractioning increases the occurrence of pulmonary fibrosis after 5 years RR 4.17 (95% CI, 1.05 to 16.56; P = 0.04). In another sub-analysis to verify the possible influence of tumor-bed radiation boost we observed that unconventional fractioning increases disease-free survival within 5 years RR 0.82 (95% CI, 0.69 to 0.97; P = 0.02), decreases distant recurrence after 5 years of the treatment RR 0.80 (95% CI, 0.66 to .96; P = 0.02) but increases the occurrence of pulmonary fibrosis after 5 years RR 4.17 (95% CI, 1.05 to 16.56; P = 0.04). Conclusion: Hypofractioning does not affect, neither in the short nor in the long term, the ocorrence of local, locoregional and distant recurrence, disease-free survival and mortality, of ischemic heart disease, pulmonary fibrosis and ribs fracture in women with early stage breast cancer that underwent breast-conserving surgery.
Citation Format: Nazário ACP, Andrade TRdM, Segreto HRC, Segreto RA, Fonseca MCM. Effect of hypofractionated radiotherapy for the treatment of early stage breast cancer: Meta-analysis on efficacy and safety. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-15.