Kao et al. calculated odds ratios for the development of oral cancer of 18.86 and 5.08 for those with the G/G (95% CI, 3.61–98.52) or A/G (95% CI, 2.64–9.76) genotype of CYP1A1, respectively, and also reported odds ratios for the development of OPMDs of 15.23 and 2.67 for those with the G/G (95% CI, 2.76–83.98) or A/G (95% CI, 1.32–5.40) genotype, respectively. Here, CYP1A1 is linked to lip and oral cavity carcinoma.