CYP2E1 and oral cavity neoplasm: Furthermore, in another Brazilian study of HNC [67], it was observed that the CYP2E1*5A/*5B (c1/c2) genotype was more frequent in oral cavity tumors than in tumors from other anatomic sites (P = 0.003) and that the CYP2E1*5A/*5A (c1/c1) genotype was more frequently detected in white patients (P = 0.0031).