Lack of association between vitamin D receptor gene BsmI polymorphism and breast cancer risk: an updated meta-analysis involving 23,020 subjects

The vitamin D receptor (VDR) is a crucial mediator for the cellular effects of vitamin D. A great number of studies regarding the association between BsmI polymorphism in the VDR gene and breast cancer have been published. However, the results have been contradicting. Therefore, we conducted a meta-analysis to re-examine the controversy. Published literatures from PubMed, Embase, and Chinese Biomedical Literature Database (CBM) were searched (updated to July 10, 2013). The principal outcome measure was the odds ratio (OR) with 95 % confidence interval (CI) for breast cancer risk associated with VDR BsmI polymorphism. With all studies involved, the meta-analysis results suggest no statistically significant association between VDR BsmI polymorphism and breast cancer risk (B vs. b, OR = 0.922, 95 % CI = 0.836–1.018, P = 0.108, I ²  = 80.0 %; BB vs. bb, OR = 0.843, 95 % CI = 0.697–1.021, P = 1.75, I ²  = 75.5 %; Bb vs. bb, OR = 0.930, 95 % CI = 0.814–1.063, P = 0.31, I ²  = 73.1 %; BB+Bb vs. bb, OR = 0.906, 95 % CI = 0.787–1.043, P = 1.37, I ²  = 78.7 %; BB vs. bb+Bb, OR = 0.899, 95 % CI = 0.786–1.028, P = 1.56, I ²  = 61.0 %). The results were not changed when studies were stratified by ethnicity or source of controls. This meta-analysis suggested that there were no associations between VDR BsmI polymorphism and breast cancer.