American Association for Cancer Research, Cancer Epidemiology, Biomarkers & Prevention, 6(22), p. 1102-1109, 2013
DOI: 10.1158/1055-9965.epi-12-1046
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Abstract Background: Diabetes mellitus (DM) increases the risk for cancer at almost all sites, but data on the association with prostate cancer are inconsistent. Methods: We assessed the risk of a prostate cancer diagnosis among men with type 2 (T2)DM in a nationwide population-based case-control study including 44,352 men with prostate cancer identified through the Prostate Cancer data Base Sweden (PCBaSe) between 2002 and 2006 and 221,495 age-matched men from the general population. Results: Overall, the risk of prostate cancer among men with T2DM was lower than among men without T2DM [OR, 0.80; 95% confidence interval (CI), 0.76–0.85]. The risk decreased with longer disease duration and was observed across all tumor risk categories, although most clearly among men with low risk tumors (OR, 0.71; 95% CI, 0.64–0.80). The risk for prostate cancer was reduced among diabetic men on dietary treatment only (OR, 0.89; 95% CI, 0.80–0.99) but more markedly among men on oral hypoglycemic agents (OR, 0.80; 95% CI, 0.74–0.87) and insulin (OR, 0.72; 95% CI, 0.69–0.81). Obese diabetic men (BMI > 30 kg/m2) showed a reduced risk (OR, 0.72; 95% CI, 0.65–0.80) compared with men without diabetes. There was a trend of decreasing risk with increasing levels of HbA1c (P < 0.05). Conclusions: This nationwide study confirmed a reduced risk of being diagnosed with prostate cancer among men with T2DM, especially for low-risk tumors. An altered hormonal milieu is a plausible explanation, although the possibility of decreased prostate cancer detection among diabetic men cannot be ruled out. Impact: This is the largest study to examine the association between T2DM and prostate cancer accounting for tumor risk group and diabetes treatment. Cancer Epidemiol Biomarkers Prev; 22(6); 1102–9. ©2013 AACR.