Objectives: There is a growing epidemiologic literature suggesting an inverse association between history of diabetes and risk of incident prostate cancer. To our knowledge, the relationship between diabetes and tumor features and risk of recurrence among men with prostate cancer has not been examined previously. We hypothesized that men with diabetes would present with more favorable prostate cancer and experience lower risk of recurrence.
Methods: We identified 691 men with diabetes at the time of prostate cancer diagnosis, among 6722 men diagnosed with prostate cancer in 1989 to 2002 within CaPSURE(TM), a community-based prostate cancer registry study. We compared clinical and socio-demographic variables by diabetes status, using chi2 tests, t-tests, and multinomial logistic regression. We examined recurrence rates for prostate cancer among patients with and without diabetes using Kaplan-Meier log-rank tests and Cox proportional hazard models.
Results: In multivariate analyses, history of diabetes was not associated with any diagnostic clinical parameter, and treatment-specific recurrence rates for prostate cancer generally did not differ by diabetes history. Among men with low-prognostic risk or who were younger at prostate cancer diagnosis, being diabetic (versus not) was associated with an elevated risk of recurrence after radiation therapy, in multivariate analyses.
Conclusions: Contrary to data suggesting that diabetes may be modestly protective against risk of incident prostate cancer, we did not observe any evidence of an inverse association between history of diabetes and aggressiveness at diagnosis or risk of recurrence, in this population of men with prostate cancer.