Abstract 3604: Diabetes and prostate cancer-specific mortality in the Multiethnic Cohort Study: Looking deeper into diagnostic timing and disease duration

Abstract Background: Diabetes is found to be associated with higher cancer-specific mortality for several cancers, but the findings have been conflicting for prostate cancer (PCa). The goal of this study was to evaluate the association between diabetes and PCa-specific mortality (PCSM) in a racial/ethnically diverse population of PCa patients. Methods: The association between diabetes and PCSM was assessed in 10, 464 African American (20.9%), Latino (23.6%), Native Hawaiian (5.4%), Japanese American (28.2%), and non-Hispanic White men (21.9%) diagnosed with incident PCa in the Multiethnic Cohort (MEC). Based on questionnaires and administrative data, diabetes status was defined as non-diabetic, pre-diagnostic diabetic, and post-diagnostic diabetic (relative to PCa diagnosis). In a subsequent analysis, diabetes status was further categorized given the timing of diabetes diagnosis (0-5 or > 5 years pre- or post-diagnosis of PCa). Sub-hazard ratios (SHRs) and 95% confidence intervals (CIs) were estimated using the Fine and Grey subdistribution hazards models, with time since PCa diagnosis as the time metric and adjustments on potential confounders. All analyses were performed in all PCa patients and stratified by tumor stage (localized, advanced) and Gleason score (high-grade, low-grade). Results: During an average follow-up of 8.5 years, 1, 311 (12.5%) men with PCa died of the disease. Compared to men without diabetes, men with pre-diagnostic diabetes had a significantly lower PCSM (SHR=0.73, 95% CI: 0.62-0.86) and the reduction in PCSM appeared to be greater for men with post-diagnostic diabetes (SHR=0.58, 95% CI: 0.48-0.70). Similar trends of the associations for pre- and post-diagnostic diabetes were observed among patients with high-grade (SHR 0.72 vs. 0.51) or advanced (SHR 0.72 vs. 0.56) disease. Among patients with low-grade or localized disease, the inverse associations with PCSM were similar for men with pre- (SHR 0.70-0.76) or post-diagnostic diabetes (SHR 0.65-0.75). Further categorization given the timing of diabetes diagnosis did not lead to differences in trends of the associations for pre- and post-diagnostic diabetes on PCSM among all, high-grade and advanced PCa cases. Among low-grade or localized cases, the inverse association was more evident among those with 5+ years of diabetes before cancer diagnosis and those who became diabetic within 5 years of cancer diagnosis (SHR 0.48-0.69 vs. 0.81-0.91). Statistical significance was defined as P < 0.05. Conclusions: We found that both pre- and post-diagnostic diabetes were significantly associated with a lower PCSM among PCa patients, and the association appeared to be stronger for post-diagnostic diabetes. Further studies are needed to confirm these findings in other multiethnic populations and to understand the mechanisms driving these associations. Citation Format: Wei (Melody) Xiong, David Bogumil, Peggy Wan, Gertraud Maskarinec, David V. Conti, Lynne R. Wilkens, Loïc Le Marchand, Christopher A. Haiman, Fei Chen. Diabetes and prostate cancer-specific mortality in the Multiethnic Cohort Study: Looking deeper into diagnostic timing and disease duration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3604.