Abstract
Objective: To investigate the risk of bladder cancer with pioglitazone, the data of diabetic patients treated at Teikyo Chiba Medical Center were analyzed retrospectively. Methods: From February 2009 to October 2011, 720 patients were treated with pioglitazone, and 742 patients were not treated with pioglitazone at Teikyo University Chiba Medical Center. The numbers of newly diagnosed bladder cancers from February 2009 to December 2013 in these patients and the occurrence of bladder cancer among type 2 diabetes mellitus patients were identified. The duration of diabetes, sex, age, smoking, and medication for diabetes were obtained from the medical records. The occurrence of bladder cancer was defined as incident cases after the initiation of pioglitazone. Statistical significance was analyzed by Fisher’s exact test. Results: About 2% of diabetic patients had bladder cancer. The incidence of bladder cancer was not different between the pioglitazone group (15/720, 2.0%) and the no pioglitazone group (14/742, 1.9%). No oral diabetes medication was related to the risk of bladder cancer. However, use of insulin was significantly related to bladder cancer risk (hazard ratio [HR]: 2.83; 95% confidence interval [CI]: 1.15–6.84; p=0.0246), and sex was also significantly related to bladder cancer (HR: 6.001; 95% CI: 1.397–43.06; p=0.0137). The duration of diabetes and smoking were not associated with bladder cancer risk. Conclusion: In this study, use of pioglitazone was not related to bladder cancer risk, while use of insulin was related
Highlights
The safety of pioglitazone, an oral anti-diabetic agent in the thiazolidinedione class, is controversial
There is some evidence suggesting that pioglitazone may be associated with an increased risk of bladder cancer
More recent data from observational studies show relative risks (RRs) ranging from 1.12 to 1.33 when diabetic patients receiving pioglitazone are compared with diabetic patients receiving other antidiabetic medicines but not exposed to pioglitazone [4]
Summary
The safety of pioglitazone, an oral anti-diabetic agent in the thiazolidinedione class, is controversial. There is some evidence suggesting that pioglitazone may be associated with an increased risk of bladder cancer. A recent observational study [3] using the Kaiser Permanente Northern California diabetes registry data found that, among 193,099 diabetic patients who were ≥40 years old, use of pioglitazone at any time (n = 30,173) was not associated with the risk of bladder cancer (adjusted HR: 1.2; 95% CI: 0.9–1.5). Two subsequently published Taiwanese studies and one Korean study found no significant association between pioglitazone and bladder cancer [7,8,9].
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