While a number of CYP2E1 variants have been analyzed in relation to cancer development, CYP2E1*5B is most often considered. Many of these associations are enhanced by alcohol or nicotine intake which further supports the role of CYP2E1 in the metabolism of these substances. The c1/c1 genotype of the CYP2E1*5B variant increased risk of hepatocellular carcinoma in smokers from a Taiwanese population (Yu et al., 1995) and oral cavity cancer in heavy smokers from Caucasians and African Americans populations (Liu et al., 2001). Conversely other studies have found evidence for the minor c2 allele leading to an increased risk of hepatocellular carcinoma in ethanol users with chronic liver disease and oral cavity cancer in combination with heavy drinking (Bouchardy et al., 2000). Others have found no association between the CYP2E1*5B variant and the same types of cancer including a number of studies for hepatocellular carcinoma (Kato et al., 1995; Lee et al., 1997; Wong et al., 2000). Many CYP2E1 association studies did not detect an association because the c2 risk allele is rare in Caucasians (2–3%) (Kato et al., 1992; Pastorelli
