Abstract LB-15: Frequency of aspirin use and prostate cancer mortality among prostate cancer cases in the control arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.

Abstract

Abstract Background: Aspirin may slow progression of cancer through the inhibition of platelet aggregation as experimental research has shown that platelets play a role in cancer cell dissemination and metastatic growth. While a 10% reduction in prostate cancer risk has been associated with regular aspirin use, only a few epidemiological studies have evaluated the association between aspirin use and prostate cancer mortality among prostate cancer cases. Methods: Participants included 3857 men, age 55-74, who were diagnosed with prostate cancer in the control arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial between 1993-2009. The frequency of aspirin use one year prior to baseline (1993-2001) was ascertained through a self-administered questionnaire. Death due to prostate cancer was ascertained by annual questionnaire and linkage to the National Death Index. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using COX proportional hazards models using age as the time metric and adjusting for clinical stage, Gleason score, primary treatment, smoking status, body mass index, race, history of heart attack, and history of stroke. Results: After a median of 5 years of follow-up, 136 cases died of prostate cancer. No significant association with prostate cancer mortality was observed between cases who reported pre-diagnostic daily or more than daily aspirin use compared to cases who reported no aspirin use (HR=0.77; 95% CI 0.48-1.25). Among those diagnosed with clinically advanced stage (III, IV) disease, an inverse association with prostate cancer mortality was observed for cases who reported daily or more than daily aspirin use (HR=0.37; 95% CI 0.15-0.92), while no association for daily or more than daily users was seen among those with clinically localized prostate cancer (HR=0.86; 95% CI 0.47-1.58). Conclusion: Pre-diagnostic use of aspirin was not significantly associated with prostate cancer mortality based on cases diagnosed in the PLCO control arm, although a reduction in risk of prostate cancer mortality was observed among those with advanced stage disease in a subgroup analysis. Citation Format: Sarah E. Daugherty, Ruth Pfeiffer, Armen Ghazarian, Grant Izmirlian, Phil Prorok, Katherine McGlynn. Frequency of aspirin use and prostate cancer mortality among prostate cancer cases in the control arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-15. doi:10.1158/1538-7445.AM2013-LB-15