Introduction: Disparities in prostate cancer (CaP) outcomes are poorly understood, but are likely caused by multiple factors. The presence of comorbidities may contribute to disparate outcomes in at least two ways: by altering the biological course of disease, and by influencing overall survival probabilities that impact treatment decisions. Diabetes has been associated with CaP in a variety of settings, and there is evidence that AA men suffer from diabetes at a higher rate than men of other races. We examined whether presence of diabetes is related to prostate cancer recurrence measured by post-prostatectomy biochemical (PSA) failure (BF).

Materials and methods: A prospective cohort of 554 European Americans (EA) and 184 African American (AA) CaP cases from the University of Pennsylvania were studied. We performed survival analysis for BF to evaluate the effect of diabetes on using Cox proportional hazards models adjusting for age, race, obesity, and Kattan score. Median post-prostatectomy follow-up was 40 months.

Results: Prevalence of diabetes was 6.3% overall (12% in AA and 5% in EA, p<0.0001). AA men were more likely to be obese then EA men (33% vs. 19%, p = 0.001). During post-prostatectomy follow-up, 52 (28%) AA and 187 (33%) EA men experienced BF; 47 (9%) diabetic men and 691 (5%) non-diabetic men experienced BF. Diabetic men were twice as likely to experience BF as men without diabetes (HR = 2.2, 95% CI: 1.26-3.92). Diabetes had a significant effect in both EA (HR = 2.1, 95% CI: 1.02-4.37) and AA (HR = 3.4, 95% CI: 1.16-10.0).

Conclusions. Being diabetic at time of CaP diagnosis increased the risk of prostate cancer recurrence, even after accounting for obesity and age. This effect was significant for both AA and EA, but the effect of diabetes appeared to be greater in AA. Diabetes may an important predictor of post-prostatectomy CaP outcomes.

Citation Format: Elaine Spangler, Charnita Zeigler-Johnson, Jonathan Mitchell, Timothy Rebbeck. Diabetes and prostate cancer (CaP): Clinical characteristics and disparity in outcomes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3720. doi:10.1158/1538-7445.AM2015-3720