Compared with non-BQ chewers with MAOA rs3027452 (A-allele), BQ chewers with MAOA rs3027452 (G-allele) had a significantly synergistic risk of oral and pharyngeal cancers (AOR = 18.57; 95% CI, 5.06–68.18). The gene discussed is MAOA; the disease is pharynx cancer.