CYP2E1 GENETIC POLYMORPHISMS AND RISK OF NASOPHARYNGEAL CARCINOMA IN TAIWAN

Background: Nasopharyngeal carcinoma occurs disproportionately among i ndividuals of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is known to activate nitrosamines and other carcinogens that are poss ibly involved in the development of this disease. Certain alleles of t he CYP2E1 gene are thought to be more highly expressed than others, an d their distribution varies between Asian and Caucasian populations. W e conducted a case-control study to investigate whether such variation s affect the risk of developing nasopharyngeal cancer. Methods: Three hundred sixty-four patients with nasopharyngeal carcinoma (96% of 378 eligible patients) and 320 control subjects (86% of 374 eligible subje cts) were studied. A risk factor questionnaire was administered to par ticipants to assess factors postulated to be linked to nasopharyngeal carcinoma, Peripheral blood was obtained from all subjects and DNA was purified from nucleated cells. A polymerase chain reaction-based rest riction fragment length polymorphism assay that used the restriction e nzymes Rsa I and Dra I was used to detect wild-type and variant forms of the CYP2E1 gene. Results: Individuals homozygous for an allele of t he CYPSE1 gene that is detected by Rsa I digestion (c2 allele) were fo und to have an increased risk of nasopharyngeal carcinoma (relative ri sk [RR] 2.6; 95% confidence interval [CI] 1.2-5.7); this effect was li mited to nonsmokers (RR = 9.3; 95% CI = 2.7-32) and was not affected b y alcohol consumption, Conclusions: Our findings suggest that the CYP2 E1 genotype is a determinant of nasopharyngeal carcinoma risk.