XRCC1 and laryngeal squamous cell carcinoma: The results showed that XRCC1 codon 399 Gln/Gln vs. Arg/Arg, Arg/Gln vs. Arg/Arg and Gln/Gln+Arg/Gln vs. Arg/Arg for Caucasians and oral squamous cell carcinoma, Gln/Gln vs. Arg/Arg for healthy population-based control and larynx squamous cell carcinoma, and Arg/Gln vs. Arg/Arg for hospital-based control and healthy population-based control had no heterogeneity with a P value ≥0.05, therefore, we analyzed the summary odds ratios for them with a fixed-effects model.