Sub-grouping showed a risk due to the PTGS2 -1195(GA+AA) genotype in males (P=0.007; odds ratio=2.97; 95% confidence interval=1.3-6.5), patients without gallstones (P=0.001; odds ratio=2.53; 95% confidence interval=1.4-4.7) and with late-onset gallbladder cancer (P=0.012; odds ratio=1.99; 95% confidence interval=1.1-3.4).