XRCC1 and head and neck squamous cell carcinoma: There were not significant associations between XRCC1 Arg194Trp polymorphism with HNSCC risk based on Caucasian or mixed ethnicity under different genetic models (p values >.05); the association was significant for Asian ethnicity under dominant genetic model so that the Trp/Trp + Arg/Trp variant was significantly associated with increased HNSCC risk compared to Arg/Arg variant.