The effect of RAD51 135 G>C and XRCC2 G>A (rs3218536) polymorphisms on ovarian cancer risk among Caucasians: a meta-analysis.

Genetic polymorphisms of RAD51 135 G>C and XRCC2 G>A (rs3218536) have been reported to change the risk of ovarian cancer, but the results are controversial. To get a more precise result, a meta-analysis was performed. A comprehensive literature search in PubMed, Excerpta Medica Database, and China National Knowledge Infrastructure was carried out to get case–control studies published up to November 2013. The pooled odds ratio (OR) and its corresponding 95 % confidence interval (CI) were conducted to estimate the effect of RAD51 135 G>C and XRCC2 G>A (rs3218536) polymorphisms on ovarian cancer risk. A total of 13 independent case–control studies with 5,927 cases and 10,303 controls were included in this meta-analysis. There was no significant association between RAD51 135 G>C polymorphism and risk of ovarian cancer. However, the result of total studies indicated the XRCC2 G>A (rs3218536) polymorphism could reduce the risk of ovarian cancer (heterozygote model AG vs. GG: OR = 0.877, 95 % CI = 0.770–0.999, P = 0.048; dominant model AA/AG vs. GG: OR = 0.864, 95 % CI = 0.763–0.979, P = 0.022). The result was still significant after Hardy–Weinberg equilibrium-violating studies were excluded (allele contrast A vs. G: OR = 0.836, 95 % CI = 0.74–0.943, P = 0.004; homozygote model AA vs. GG: OR = 0.562, 95 % CI = 0.317–0.994, P = 0.048; heterozygote model AG vs. GG: OR = 0.859, 95 % CI = 0.753–0.98, P = 0.023; dominant model AA/AG vs. GG: OR = 0.842, 95 % CI = 0.74–0.958, P = 0.009). In the stratified analysis by ethnicity, significantly reduced risk was observed among Caucasians in dominant model (AA/AG vs. GG: OR = 0.867, 95 % CI = 0.764–0.984, P = 0.027). No significant association was found between the RAD51 135G>C polymorphism and the risk of ovarian cancer. Interestingly, XRCC2 G>A (rs3218536) polymorphism might reduce the risk of ovarian cancer. Larger-scale and well-designed studies are needed to further clarify the association.