Tobacco use and occupational exposure to carcinogens, but not N-acetyltransferase 2 genotypes are major risk factors for bladder cancer in the Japanese

Our study investigated the risks of genotypes of N-acetyltransferase 2 (NAT 2), tobacco use and/or occupational exposure to carcinogens in patients wit h bladder cancer and in age- and sex-matched controls in Japanese. NAT2 gen otypes were categorized into two groups, homozygous mutant (slow acetylator genotype) and homozygous and heterozygous wild type (fast acetylator genot ype). The percentage of NAT2 slow acetylator types was 6.7% in the bladder cancer patients, close to the value for controls (6.1%). There was no assoc iation between NAT2 slow acetylator genotype and the risk of bladder cancer . This association was also insignificant when subjects were restricted to those who used tobacco or those occupationally exposed to carcinogens. In c ontrast, tobacco use in combination with exposure to carcinogens was a sign ificant risk factor, as based on the odds ratio and chi-square test. The co mbination of both factors should be an additive risk factor for bladder can cer. In this study, we demonstrated that the environmental factors of smoki ng habit and occupational exposure for carcinogenicity are much more import ant than genetic factors in bladder cancer.