Risk of NPC associated with the BIRC5 -31C/G polymorphism by potential risk factors in the Guangxi population.

Due to genotyping failure, the actual sample size was 844 and 1021 for the cases and controls, respectively. OR, odds ratio; CI, confidence interval.1Number of genotype in cases/number of genotype in controls.2The ORs and P values were calculated by logistic regression with the CG + GG genotype as the reference group and adjusted for age, sex, smoking and drinking status, smoking level, nationality and family history where appropriate within the strata.3For difference in ORs within each stratum.