Association between calcium channel blockers and breast cancer: a meta-analysis of observational studies

Objective To investigate the association between calcium channel blockers (CCBs) and increased risk of breast cancer. Methods Using terms related to breast cancer and CCB, we searched PubMed, Embase, and Web of Science for studies on CCB use and the associated risk of breast cancer published before July 2013. Two evaluators independently selected observational studies on the basis of predetermined selection criteria, and 11 studies were included in the meta-analysis. Summary estimates were obtained using fixed-effects or random-effects models as appropriate, and subgroup analyses, sensitivity analyses, and publication bias tests were performed. Results Our meta-analysis consisted of 11 studies, including four case-controls, two nested case-controls, and five cohort studies. The odds ratios (ORs) of the association between CCB use and breast cancer were 1.11 (95% confidence interval [CI] 0.93-1.33) overall, 1.04 (95% CI 0.92-1.18) for prospective studies, and 1.33 (95% CI 0.79-2.25) for retrospective studies. There was a positive association between immediate-release CCB use and risk of breast cancer (OR 1.88, 95% CI 1.37-2.60). Conclusions There is no evidence that CCB use is associated with an increased risk of breast cancer. However, there may be a positive association between immediate-release CCB use and risk of breast cancer, but given the current preference for use of sustained-release CCB, the potential clinical impact of this association is limited. Copyright (C) 2014 John Wiley & Sons, Ltd.