RESUMEN
Background: Previously published data on any association of the fat mass and obesity-associated (FTO) gene with breast cancer risk remain inconclusive. Therefore, we conducted the present meta-analysis of links between breast cancer and the FTO rs9939609 polymorphism. Methods: We have conducted a systematic review of the English literature by searching PubMed, Google Scholar and ISI Web of Knowledge databases for studies on associations between the FTO rs9939609 polymorphism and breast cancer risk. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the strength of the association using fixed- or random-effects model. Results: We included five studies with 1134 cases and 1453 controls. Overall, no significant association between the FTO rs9939609 polymorphism and risk of breast cancer was found. On subgroup analysis by ethnicity, there was still no significant association detected. Conclusions: To our knowledge, this is the first meta-analysis of the FTO rs9939609 polymorphism and risk of breast cancer. However, the present meta-analysis suggested that only there might be a significant association of the CXCL12 rs1801157 polymorphisms with breast cancer risk.
RESUMEN
Background: A number of case-control studies have evaluated associations between the X-ray cross complementary group 1 protein (XRCC1) gene rs1799782 (Arg194Trp), rs25487 (Arg399Gln) and rs25489 (Arg280His) polymorphisms and thyroid cancer (TC) risk, but the results remain inconclusive. Materials and Methods: A systematic literature search was performed using PubMed and Google Scholar Search. According to defined criteria data were extracted and pooled odds ratios with 95% confidence intervals were calculated under five genetic models. Results: A total of 8 studies with 1,672 cases and 2,805 controls for the rs1799782 polymorphism, 14 studies with 2,506 cases and 5,180 controls for the rs25487 polymorphism, and 11 studies with 2,197 cases and 4,761 controls for the rs25489 polymorphism were included in this meta-analysis. Overall, there was a statistical association between XRCC1 rs1799782 polymorphism and TC risk with the homozygote genetic model (TT vs. CC: OR = 1.815, 95% CI = 1.115-2.953, p= 0.016) and the recessive genetic model (TT vs. TC+CC: OR = 1.854, 95% CI = 1.433-2.399, p= <0.001). In the subgroup analysis by ethnicity, significantly increased TC risk was observed only in Asians under the recessive model (TT vs. TC+CC: OR = 1.816, 95% CI = 1.398-2.358, p= <0.001). In addition, there was no positive association between XRCC1 rs25487 and rs25489 polymorphisms and risk of TC. However, there was a significant association between XRCC1 rs25487 polymorphism risk of TC among Caucasians with allele genetic comparison (A vs. G: OR= 0.882, 95% CI = 0.794-0.979, p= 0.136) and dominant genetic comparison (AA+AG vs. GG: OR=0.838, 95% CI = 0.728-0.965, p= 0.014). Conclusions: The results of our meta-analysis suggest an increased risk of TC with the XRCC1 rs1799782 and rs25487 polymorphisms. However, the XRCC1 rs25489 polymorphism appeared to be without influence.