Compared to the healthy control group with rs9605030 C/C+C/T, BQ chewers with the COMT (rs9605030) risk T/T genotype had a significantly synergistic risk of oral and pharyngeal cancers (AOR = 31.57; 95% CI, 6.10–163.34) and risk of OPMD (AOR = 32.29, 95% CI = 3.28–317.97). The gene discussed is COMT; the disease is pharynx cancer.