EFFECT OF HYPOFRACTIONATED RADIOTHERAPY AS A TREATMENT OF EARLY STAGE BREAST CANCER IN RELATION TO SECURITY

Objectives: To evaluate the short and long term effect of hypofractionated radiotherapy on security 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 ischemic heart disease, ribs fracture and lung fibrosis. Results: We included two medium/ high quality studies totalizing 4,451 women. Unconventional fractioning does not change within 5 years and after 5 years, respectively: (1) 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); (2) cardiac ischemia (radiotherapy only in the left breast) RR de 0.84 (95% CI; 0.21 to 3,.7; P= 0.80) e RR de 0.72 (95% CI, 0.28 to 1.86; P= 0.49); (3) ribs 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); (4) pulmonary fibrosis RR 2.42 (95% CI 0.50 to 11.71, P = 0.27) and RR 0.97 (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). This increase was also observed with use tumor-bed radiation boost. Conclusion: Hypofractioning does not affect the occurrence of ischemic heart disease, pulmonary fibrosis and ribs fracture in women with early stage breast cancer that underwent breast-conserving surgery.