Glycemic control and prostate cancer progression: results from the SEARCH database

Several studies have examined the association between diabetes mellitus (DM) and prostate cancer (PCa) risk and progression, however nearly all of these studies have compared diabetic versus non-diabetic men. We sought to investigate the role of glycemic control, as measured by HbA1c, on PCa aggressiveness and prognosis in men with DM and PCa from the Shared Equal Access Regional Cancer Hospital (SEARCH) database.

We identified 247 men in SEARCH with DM and a recorded HbA1c value within the 12 months prior to radical prostatectomy between 1988 and 2009. We divided these men into tertiles by HbA1c level. The associations between HbA1c tertiles and risk of adverse pathology and biochemical recurrence were tested using multivariate logistic regression and Cox proportional hazards models, respectively.

Median HbA1c level was 6.9. On multivariate analysis, HbA1c tertiles were predictive of pathological Gleason score (P-trend = 0.001). Relative to the first tertile, men in the second (OR 4.68, P = 0.003) and third tertile (OR 6.60, P < 0.001) were more likely to have Gleason score > or = 4 + 3. HbA1c tertiles were not associated with margin status, node status, extracapsular extension or seminal vesicle invasion (all P-trend > 0.2). In the multivariate Cox proportional hazards model, increasing HbA1c tertiles were not significantly related to risk of biochemical recurrence (P-trend = 0.56).

Men with higher HbA1c levels presented with more biologically aggressive prostate tumors at radical prostatectomy. Although risk of recurrence was unrelated to HbA1c levels, further studies are needed to better explore the importance of glycemic control on long-term outcomes in diabetic men with PCa.