Abstract A6: Ethnic differences in risk of lung cancer associated with repair capacity for tobacco carcinogen-induced DNA adduct

Abstract

Abstract Lung cancer is initiated by tobacco carcinogens-induced DNA damage, such as DNA adducts caused by benzo[a]pyrene diol epoxide (BPDE). These adducts can be removed by an efficient nucleotide excision repair. We have previously reported that DNA repair capacity (DRC) measured by the host-cell reactivation assay is associated with risk of lung cancer in non-Hispanic whites. In the recent analysis with larger sample sizes including minorities, we found that the suboptimal DRC remains associated with increased risk of lung cancer in 1730 cases and 1683 controls of non-Hispanic whites. The mean values of DRC were 8.37% ± 2.8% (SD) in the cases vs. 9.04% ± 3.1% in the controls (P < 0.0001). The odds ratio (OR) was 1.42 (95% confidence interval [CI], 1.24 – 1.64) after adjustment for age, sex, pack-years of smoking, family history of cancer, and other assay-related covariates. The similar results and risk trend have been also found in 127 Mexican-American patients with lung cancer and 176 cancer-free controls with a mean DRC of 8.38% ± 2.7% in the cases vs. 9.04% ± 3.3% in the controls, and an adjusted OR of 1.67 (95% CI, 1.00 – 2.78), although the difference in mean DRC values was borderline significant (P = 0.056) because of the relatively small sample size. However, this difference in DRC for tobacco carcinogen-induced DNA adducts was not significant in 327 African-American patients with lung cancer and 325 cancer-free controls. The mean values of DRC were 8.90% ± 3.1% in the cases vs. 8.66% ± 2.8% in the controls (P = 0.301). The adjusted OR was 0.99 (95% CI, 0.70 – 1.39). The DRC level in African-American controls was non-significantly lower than other ethnic controls (P = 0.144); however, African-American patients had significantly higher DRC than non-Hispanic white patients and Mexican-Americans patients (P = 0.053). The results further confirmed that low DRC is associated with increased risk of lung cancer in non-Hispanic whites and also provided the evidence of this association in Mexican Americans. These findings help us understand the ethnic differences in the development of lung cancer. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A6.