Type 2 diabetes and the risk of mortality among patients with prostate cancer.

Purpose: The aim of this study was to determine whether type 2 diabetes is associated with the incidence of prostate cancer mortality and all-cause mortality.

Methods: This study was conducted by linking four databases from the United Kingdom: the National Cancer Data Repository, the Clinical Practice Research Datalink, the Hospital Episodes Statistics database, and the Office for National Statistics database. The cohort consisted of men newly diagnosed with non-metastatic prostate cancer between 1 April 1998 and 31 December 2009, followed until 1 October 2012. Cox proportional hazard models were used to estimate adjusted hazard ratios with 95 % confidence intervals (CIs) of prostate cancer mortality and all-cause mortality comparing patients with to without type 2 diabetes. All models were adjusted for a number of potential confounders, which included excessive alcohol use, smoking, comorbidities, and prostate cancer-related variables.

Results: The cohort consisted of 11,920 patients, which included 1,132 (9.5 %) with preexisting type 2 diabetes. During a mean follow-up of 4.7 (SD 3.0) years, there were 3,605 deaths (incidence rate: 6.4 %/year) including 1,792 from prostate cancer (incidence rate: 3.3 %/year). Type 2 diabetes was associated with a 23 % increased risk of prostate cancer mortality (HR 1.23, 95 % CI 1.04-1.46) and a 25 % increased risk in all-cause mortality (HR 1.25, 95 % CI 1.11-1.40).

Conclusions: The results of this large population-based study indicate that type 2 diabetes is associated with an increased risk of prostate cancer mortality and all-cause mortality, which may signal an association between hyperinsulinemia or other diabetes-associated metabolic derangements and cancer aggressivity.