PD13-10: Diabetes and prostate cancer outcomes in men with nonmetastatic castrate-resistant prostate cancer: Results from the SEARCH Cohort

Andrei Sergeyev*, Lin Gu, Amanda De Hoedt, Durham, NC, Christopher Amling, Portland, OR, William Aronson, Los Angeles, CA, Matthew Cooperberg, San Francisco, CA, Christopher Kane, San Diego, CA, Zachary Klaassen, Martha Terris, Augusta, GA, Lourdes Rivera, San Juan, Puerto Rico, Stephen Freedland, Ilona Csizmadi, Los Angeles, CA

Introduction: Men with non-metastatic castration-resistant prostate cancer (nmCRPC) have a poor prognosis with a third of patients developing metastases or dying within a median of 2.5 years. Given the substantial overlap between diabetes and PC in elderly men, a large body of research has investigated the relation between diabetes and PC risk; however, the association between diabetes and PC progression, particularly among men with more advanced disease, has been under-studied. To address this gap, we studied the association between diabetes and the development of metastases, PC-specific mortality (PCSM) and all-cause mortality (ACM) in men with nmCRPC. We also tested if associations were modified by race.

Methods: Men with nmCRPC between 2000-2017 at 8 Veterans Affairs hospitals in the SEARCH Cohort were included. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models to test associations between diabetes and outcomes adjusted for age, race, body mass index, hospital site, biopsy grade, log-transformed PSA, and primary localized treatment. Competing risk analyses were carried out for PCSM. Interactions between diabetes and race (Black vs White) were assessed for all outcomes and evaluated for statistical significance.

Results: Of 984 men (median age: 76 years), 153 (15%) had a history of diabetes, 667 (68%) of men were White, 284 (29%) were Black and 33 (3%) were classified as ‘Other’ At baseline, median prostate specific antigen levels were 4.50 ng/mL. During a median follow-up of 6.5 years, 567 men were diagnosed with metastases, and 485 PCSM and 745 ACM events occurred. In multivariable-adjusted models, diabetes was associated with a reduced risk of metastasis (HR=0.73; 95%CI: 0.56-0.94), PCSM (HR= 0.63; 95%CI: 0.45-0.87) and ACM (HR=0.74; 95%CI: 0.58-0.93). Interactions between diabetes and race (White vs. Black men) were not statistically significant for any of the outcomes (p>0.05).

Conclusions: Among men with nmCRPC, we found that diabetes was protective against metastatic disease and mortality. While unexpected, the findings are analogous to studies that have reported diabetes to be protective for PC risk and further suggest a link between diabetes and PC that merit additional investigation.

Source of Funding: None.