ABSTRACT
BACKGROUND: After accounting for smoking history lung cancer incidence is greater in African Americans than Whites. In the Multiethnic Cohort, total nicotine equivalents (TNE) are higher in African Americans than Whites at similar reported cigarettes per day (CPD). Greater toxicant uptake per cigarette may contribute to the greater lung cancer risk of African Americans. METHODS: In a nested case-control lung cancer study within the Southern Community Cohort, smoking-related biomarkers were measured in 259 cases and 503 controls (40% White, 56% African American). TNE, the trans-3-hydroxycotinine:cotinine ratio, 4-(methylnitrosamino)-1-3-(pyridyl)-1-butanol (NNAL), mercapturic acid metabolites of volatile organic compounds, phenanthrene metabolites, cadmium, and (Z)-7-(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopenyl]hept-5-enoic acid (8-iso-PGF2α) were quantified in urine. Unconditional logistic regression was used to estimate the odds ratios and 95% confidence intervals for each biomarker and lung cancer risk. RESULTS: TNE, NNAL and cadmium were higher in cases than controls (adjusted for age, race, sex, body mass index (BMI) and CPD). Among cases, these levels were higher in African Americans compared to Whites. After accounting for age, sex, BMI and pack-years, a one-SD increase in log-TNE (OR=1.30; 95% CI: 1.10-1.54) and log-NNAL (OR=1.27; 95% CI: 1.03-1.58 with TNE adjustment) were associated with lung cancer risk. In this study, where NNAL concentration is relatively high, the association for log-TNE was attenuated after adjustment for log-NNAL. CONCLUSION: Smoking-related biomarkers provide additional information for lung cancer risk in smokers beyond smoking pack-years. IMPACT: Urinary NNAL, TNE and cadmium concentrations in current smokers, particularly African American smokers, may be useful for predicting lung cancer risk.
