Abstract 4947: Aspirin use and risk of lethal prostate cancer in the Atherosclerosis Risk in Communities cohort

Background: Aspirin is commonly used to treat pain and inflammation, and is recommended for some individuals for prevention of cardiovascular disease (CVD) and colorectal cancer. Observational studies suggest that aspirin use may also lower risk of prostate cancer. However, there is limited evidence on whether aspirin may protect against lethal prostate cancer in particular, and on whether benefits are consistent in black and white men. This study sought to determine the association between aspirin use and risk of total and lethal prostate cancer, overall and by race, among men in the Atherosclerosis Risk in Communities (ARIC) cohort. Methods: The ARIC study enrolled individuals from four U.S. communities in 1987-89. This analysis was restricted to white and black men from this cohort who had non-missing data on aspirin use and were cancer-free at baseline. Aspirin use was assessed at four study visits (V1: 1987-89, V2: 1990-92, V3: 1993-95, V4: 1996-98). Indication for aspirin use was reported at V4. Cancer outcomes were ascertained through 2012. Cox proportional hazards regression was used to estimate cause-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for total incident prostate cancer and lethal prostate cancer, defined as cancer that was advanced at diagnosis or fatal during follow-up. Models were adjusted for race, study center, year of birth, education, and family history of prostate cancer (time-fixed), and smoking status, body mass index, use of statins, diabetes, and coronary heart disease (time-varying). Stratified models and likelihood ratio tests were used to test for effect modification by race. Results: There were 6,594 men (5,060 white, 1,534 black) included in this analysis. Aspirin use was reported by 29%, 33%, 37% and 44% of men at V1, V2, V3, and V4, respectively. Through the end of 2012, 817 total incident prostate cancers, including 97 lethal prostate cancers, were diagnosed. Aspirin use was not associated with risk of total prostate cancer (HR 1.06, 95% CI 0.91-1.23). However, aspirin use was inversely associated with risk of lethal prostate cancer (HR 0.58, 95% CI 0.35-0.95). This association was consistent among both white men (HR 0.64, 95% CI 0.36-1.13) and black men (HR 0.47, 95% CI 0.16-1.35, p-interaction=0.45). When looked at by indication for use, the inverse association with lethal prostate cancer appeared to be only among men who reported using aspirin regularly for CVD prevention (HR 0.63, 95% CI 0.27-1.50). Conclusions: Aspirin use was inversely associated with lethal prostate cancer, but not total prostate cancer, in this study population. The association was not modified by race and was possibly restricted to men who used aspirin regularly for CVD prevention. Support: NHLBI, NCI, NPCR Citation Format: Lauren M. Hurwitz, Corinne E. Joshu, John R. Barber, Anna E. Prizment, Mara Z. Vitolins, Miranda R. Jones, Aaron R. Folsom, Misop Han, Elizabeth A. Platz. Aspirin use and risk of lethal prostate cancer in the Atherosclerosis Risk in Communities cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4947.