Risk of prostate cancer across different racial/ethnic groups in men with diabetes: a retrospective cohort study

Aim To examine the associations between prostate cancer, diabetes and race/ethnicity. Methods Using administrative data from British Columbia, Canada for the period 1994 to 2012, we identified men aged ≥50 years with and without diabetes. Validated surname algorithms identified men as Chinese, Indian or of other race/ethnicity. Multivariable Cox regression was used to estimate adjusted risks of prostate cancer according to diabetes status and race/ethnicity. Results Our cohort of 160 566 men had a mean (sd) age of 64.7 (9.4) years and a median of 9 years’ follow-up. The incidence rates of prostate cancer among those with and without diabetes were 177.4 (171.7–183.4) and 216.0 (209.7–222.5) per 1000 person-years, respectively. The incidence among Chinese men was 120.9 (109.2–133.1), among Indian men it was 144.1 (122.8-169.0) and in men of other ethnicity it was 204.8 (200.2–209.5). Diabetes was independently associated with a lower risk of prostate cancer (adjusted hazard ratio 0.82, 95% CI 0.78–0.86), as was Chinese (adjusted hazard ratio 0.54, 95% CI 0.46,0.63) and Indian (adjusted hazard ratio 0.66, 95% CI 0.49,0.89) race/ethnicity; however, there was no statistically significant interaction between diabetes status and race/ethnicity (all P>0.1). Conclusion Diabetes and Chinese and Indian race/ethnicity were each independently associated with a lower risk of prostate cancer. This article is protected by copyright. All rights reserved.