Abstract
There is a lot of debate on the relationship between vitamin D receptor polymorphisms and risk of breastcancer. Herein, we quantitatively analyzed the published case-control studies on this relationship by metaanalysis,performing a bibliographic search from Pubmed and CNKI up to July 31, 2013. The included casecontrolstudies for Fok1, Bsm1, Taq1, Apa1, Cdx2 and Poly-A were 16, 19, 20, 10, 4, 6, respectively. Crude andadjusted odd ratios and 95% confidence intervals were calculated to present and compare the strength of anyassociations. The results of combined analyses indicated that Fok1, Bsm1, Apa1, Cdx2 and Poly-A were notsignificantly associated with the risk of breast cancer. In contrast, the tt genotype of Taq1 was a modest riskfactor for breast cancer development (tt vs. TT: OR = 1.21, 95% CI: 1.01-1.44). To further confirm the aboveresults, adjusted effects for the six polymorphisms were pooled based on adjusted ORs reported in the originalstudies. Adjusted ORs of Fok1, Apa1, Cdx2 and Poly-A were similar to the crude ORs. However, Bsm1 and Taq1showed inconsistent results. For Bsm1, OR for BB vs. bb was 0.85, 95% CI: 0.74-0.98; for Taq1, OR for tt vs.TT was 1.03, 95% CI: 0.92-1.15, and not associated with risk. Subgroup analyses for crude ORs showed someassociation between Bsm1, Taq1 and breast cancer in Caucasians only, but for adjusted ORs, no associationswere found. This meta-analysis suggests that the roles that Fok1, Apa1, Cdx2 and Poly-A polymorphisms play inbreast cancer risk are negligible, with Bsm1 and Taq1 as possible exceptions. To be conservative, we still assumedthat they may play a modest role in determining breast cancer risk. Further studies are needed to validate ourfindings.
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