Abstract 11655: Long Term Cardiovascular Mortality After Radiotherapy for Breast Cancer: A Meta-Analysis

Abstract

Introduction: Cardiovascular disease (CVD) is a late complication of radiotherapy (RT); the mean cardiac dose from irradiation of a left-sided breast cancer is much higher than that for a right-sided breast cancer. However, there is limited knowledge regarding the long-term risk of RT on CVD mortality. This study sought to investigate the use of RT for breast cancer and its association with CVD mortality, in the context of the laterality of breast cancer. Hypothesis: Long term cardiac mortalty with left-sided breast cancer radiotherapy is much higher than that for a right-sided breast cancer. Methods: Databases were searched from their inception through December 2013. Studies reporting CVD mortality with left versus right sided breast RT were included. Two authors reviewed the studies, abstracted the data and checked for accuracy, quality and strength of evidence. The outcome of interest was CVD mortality. We calculated summary risk ratio (RR) and 95% confidence intervals (CI) with the random effects model. Results: The analysis included 289,109 patients from 13 observational studies. Women, who had received RT for left-sided breast cancer, had a higher risk of CVD death than those who received RT for a right-sided breast cancer (RR 1.12, 95% CI: 1.07 to 1.18). Difference in CVD mortality between left versus right breast RT was more apparent after 15 years of follow up (RR 1.23, 95% CI: 1.08 to 1.41). Conclusions: Mortality from CVD with left sided RT was significantly higher compared to right sided RT for breast cancer; this difference was more apparent after at least 15 years of follow up.