Abstract PO-204: Cigarette smoking and risk of prostate cancer in the Multiethnic Cohort Study
Authors: Wang Anqi , Wan Peggy , Stram Daniel O. , Wilkens Lynne R. , Marchand Loic Le , Haiman Christopher A. 
Published: January 2022

Abstract
Evidence regarding the association of cigarette smoking and prostate cancer (PCa) risk has been mixed and mostly based on studies in White populations. To provide additional information on the topic, we assessed the relation between smoking and PCa risk and mortality in a large multi-ethnic population, while considering the effect of PSA screening. We included 74,598 White, African American, Native Hawaiian, Japanese American, and Latino men from the Multiethnic Cohort Study in Hawaii and California (1993-2017). During 21.5 years of follow-up, we documented 8,696 PCa cases and 1,171 deaths from PCa. Smoking status, pack years, and age at initiation were obtained at baseline. Total nicotine equivalents (TNE) for smokers were imputed by an algorithm developed based on a subset of participants (n=2,239) who measured urine TNE. We used multivariable-adjusted Cox proportional hazard regression for all time-to-event analysis. Overall, 52.0% and 18.0% of the study population were current and former smokers, respectively. African Americans had the highest proportion of ever smokers at 75.6%, while Whites had the lowest proportion at 67.7%. Compared to never smokers, current smokers had a significantly lower risk of total PCa [hazard ratio (HR)=0.83, 95% confidence interval (CI):0.78-0.89], low-grade PCa (HR=0.80, 95%CI:0.74-0.87), and localized PCa (HR=0.75, 95%CI:0.70-0.82), but higher risks of metastatic PCa (HR=1.33, 95%CI:0.99-1.77) and PCa mortality (HR=1.38, 95%CI:1.15-1.65); former smokers had intermediate risks (total HR=0.94; low-grade HR=0.94; localized HR=0.93; metastatic HR= 1.12; mortality HR=1.00). Higher smoking intensity, as measured by greater pack-year, TNE level, and younger age at initiation, respectively, were all associated with decreased risks of total PCa, low-grade, and localized PCa and increased risks of metastatic PCa and PCa mortality (trend p&lt;0.05). When stratified by race/ethnicity, current smokers in African American did not show as strong an inverse association with total PCa (HR=1.00, 95%CI:0.87-1.14) as current smokers in other races/ethnicities (HRs&lt;1). Among men who completed a question regarding PSA screening history (n=56,434), current smokers had a lower odds of reporting a PSA test (OR=0.67, p&lt;0.001) than never smokers, while former smokers had a higher odds (OR=1.04, p=0.06). In stratifying by PSA screening history, the results for men without a PSA screening were similar to the main analysis. However, among men who reported PSA screening, the inverse associations between smoking and risk of total, low-grade, and localized PCa were closer to null, while the associations with metastatic PCa and PCa mortality were positive and consistent with the main results. Lower PSA screening among smokers could partially explain the inverse association of smoking with total and low grade/stage PCa. Smoking was found to be related to higher risks of metastatic PCa and PCa mortality, independent of PSA screening.
Citation Format: Anqi Wang, Peggy Wan, Daniel O. Stram, Lynne R. Wilkens, Loic Le Marchand, Christopher A. Haiman. Cigarette smoking and risk of prostate cancer in the Multiethnic Cohort Study [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-204.