The combined results of the relevant studies exhibited that no significant associations with DTC risk were demonstrated for polymorphisms in XRCC1 Arg399Gln, Arg194Trp and Arg280His in all genetic models.
Our results suggest that XRCC1 Arg399Gln polymorphism is not associated with differentiated thyroid carcinoma risk, while a decreased risk is observed among Caucasian population.
No significant associations were observed between Arg399Gln and DTC risk in all genetic models within the overall and subgroup meta-analyses, while the Trp/Trp vs Arg/Arg and recessive model of the Arg194Trp polymorphism was associated with DTC susceptibility, and the dominant model of Arg280His polymorphism contributed to DTC susceptibility in Caucasians.
Additionally, our results support the protective role of Arg194Trp polymorphism in developing PTC, and show evidence of an association between Arg399Gln polymorphism and decreased risk of DTC in mixed population.
Multivariate analysis demonstrated a decreased risk of DTC for the Arg399Gln homozygous polymorphic (AA) genotype (OR: 0.5, 95% CI: 0.3-0.8) and the polymorphic (A) allele (OR: 0.7, 95% CI: 0.5-1.0).