Evaluation of association studies and a systematic review and meta-analysis of CYP1A1 T3801C and A2455G polymorphisms in breast cancer risk

BACKGROUND: Nine previous meta-analyses have been published to analyze the CYP1A1 T3801C and A2455G polymorphisms with BC risk. However, they did not assess the credibility of statistically significant associations. In addition, many new studies have been reported on the above themes. Hence, we conducted an updated systematic review and meta-analysis to further explore the above issues. OBJECTIVES: To explore the association on the CYP1A1 T3801C and A2455G polymorphisms with BC risk. METHODS: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (The PRISMA) were used. RESULTS: In this study, there were 63 case–control studies from 56 publications on the CYP1A1 T3801C polymorphism (including 20,825 BC cases and 25,495 controls) and 51 case–control studies from 46 publications on the CYP1A1 A2455G polymorphism (including 20,124 BC cases and 29,183 controls). Overall, the CYP1A1 T3801C polymorphism was significantly increased BC risk in overall analysis, especially in Asians and Indians; the CYP1A1 A2455G polymorphism was associated with BC risk in overall analysis, Indians, and postmenopausal women. However, when we used BFDP correction, associations remained significant only in Indians (CC vs. TT + TC: BFDP < 0.001) for the CYP1A1 T3801C polymorphism with BC risk, but not in the CYP1A1 A2455G polymorphism. In addition, when we further performed sensitivity analysis, no significant association in overall analysis and any subgroup. Moreover, we found that all studies from Indians was low quality. Therefore, the results may be not credible. CONCLUSION: This meta-analysis strongly indicates that there is no significant association between the CYP1A1 T3801C and A2455G polymorphisms and BC risk. The increased BC risk may most likely on account of false-positive results.