X-Ray Repair Cross-Complementing Group 1(XRCC1) Genetic Polymorphisms and Thyroid Carcinoma Risk: a Meta-Analysis

A number of studies have been conducted to explore the association of XRCC1 polymorphisms with thyroidcancer risk, but the results have been inconsistent. Thus we performed the present meta-analysis to clarify thisissue based on all of the evidence available to date. Relevant studies were retrieved by searching PubMed andstatistical analysis conducted using Stata software. Nine studies were included in this meta-analysis (1,620 casesand 3,557 controls). There were 6 studies (932 cases and 2,270 controls) of the Arg194Trp polymorphism, 7 studies(1432 cases and 3356 controls) of the Arg280His polymorphism and 9 studies (1,620 cases and 3,557 controls) forthe Arg399Gln polymorphism. No association of XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphismwith thyroid cancer risk was observed in the overall analysis. However, subgroup analysis revealed: 1) anelevated risk in aa vs AA analysis (OR=2.03, 95%CI= 1.24-3.31) and recessive genetic model analysis (OR=1.93,95%CI= 1.20-3.08) in the larger sample size trials for XRCC1 Arg194Trp polymorphism; 2) a decreased thyroidcancer risk on subgroup analysis based on ethnicity in Aa vs AA analysis (OR=0.84, 95%CI= 0.72-0.98) and ina dominant genetic model (OR=0.84, 95%CI= 0.72-0.97) in Caucasian populations for the XRCC1 Arg399Glnpolymorphism; 3) a decreased thyroid cancer risk on subgroup analysis based on design type in Aa vs AA analysis(OR=0.72, 95% CI= 0.54-0.97) among the PCC trials for the Arg399Gln polymorphism. Our results suggest thatthe XRCC1 Arg399Gln polymorphism may be associated with decreased thyroid cancer risk among Caucasiansand XRCC1 Arg194Trp may be associated with a tendency for increased thyroid cancer risk in the two largersample size trials.