Background: Diabetic patients have a higher risk of bladder cancer and benign prostatic hyperplasia (BPH).\r\nTheoretically, BPH patients may have an increased risk of bladder cancer because residual urine in the bladder\r\nsurely increases the contact time between urinary excreted carcinogens and the urothelium. However, whether BPH\r\nincreases bladder cancer risk in patients with type 2 diabetes has not been studied.\r\nMethods: The reimbursement databases of all Taiwanese diabetic patients under oral anti-diabetic agents or insulin\r\nfrom 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006 and\r\na total of 547584 men with type 2 diabetes were followed up for bladder cancer incidence until the end of 2009.\r\nIncidences of bladder cancer for BPH by status and by duration were calculated and adjusted hazard ratios\r\n(95% confidence intervals) were estimated by Cox regression. The effects of diabetes duration and medications\r\nused for diabetic control in relation with bladder cancer risk were also evaluated by Cox regression in BPH men.\r\nResults: The incidences were 258.77 and 69.34 per 100,000 person-years for patients with and without BPH,\r\nrespectively, adjusted hazard ratio 1.794 (1.572, 2.047). For BPH patients, those who underwent surgical procedures\r\nfor BPH had a higher incidence than those who did not (355.45 vs. 250.09 per 100,000 person-years), respective\r\nadjusted hazard ratios: 2.459 (1.946, 3.109) and 1.709 (1.492, 1.958). The significantly higher risk could be\r\ndemonstrated for BPH of any duration: respective adjusted hazard ratios 1.750 (1.430, 1.605), 1.844 (1.543, 2.203),\r\n2.011 (1.680, 2.406) and 1.605 (1.341, 1.921) for BPH <1, 1ââ?¬â??3, 3ââ?¬â??5 and =5 years versus patients without BPH.\r\nSensitivity analyses for patients aged =60 years and after excluding BPH patients with surgical procedures or\r\nwithout surgical procedures, respectively, yielded similar results. In BPH men, diabetes duration was not significantly\r\nrelated with bladder cancer; but metformin was consistently associated with a significantly lower risk, with adjusted\r\nhazard ratio of 0.719 (0.590, 0.875) for all ages and 0.742 (0.604, 0.912) for age =60 years.\r\nConclusions: BPH is a significant risk factor for bladder cancer in men with type 2 diabetes. Metformin may protect\r\nagainst bladder cancer in BPH men.
Loading....