More data implicate diabetes agent in increasing bladder cancer risk

June 13, 2012

New data have added to previous evidence that the use of pioglitazone (Actos) appears to be associated with an increased risk of incident bladder cancer among patients with type 2 diabetes, Canadian researchers recently reported.

New data have added to previous evidence that the use of pioglitazone (Actos) appears to be associated with an increased risk of incident bladder cancer among patients with type 2 diabetes, Canadian researchers recently reported.

In August 2011, the FDA approved updated drug labels for the pioglitazone-containing medicines to include safety information that the drug’s use for more than 1 year may be associated with an increased risk of bladder cancer.

In the current study, first author Laurent Azoulay, PhD, of Jewish General Hospital, Montreal, and colleagues studied patients from more than 600 general practices in the United Kingdom. The cohort consisted of patients with type 2 diabetes who were newly treated with oral hypoglycemic agents between January 1988 and December 2009.

All incident cases of bladder cancer occurring during follow-up were identified and matched to up to 20 controls on year of birth, year of cohort entry, sex, and duration of follow-up. Exposure was defined as ever use of pioglitazone, along with measures of duration and cumulative dosage.

The cohort included 115,727 new users of oral hypoglycemic agents, with 470 patients diagnosed as having bladder cancer during follow-up (rate, 89.4 per 100,000 person years). The 376 cases of bladder cancer that were diagnosed beyond 1 year of follow-up were matched to 6,699 controls.

Overall, ever use of pioglitazone was associated with an increased rate of bladder cancer (rate ratio=1.83; 95% CI: 1.10 to 3.05). The rate increased as a function of duration of use, with the highest rate observed in patients exposed for more than 24 months (rate ratio=1.99; 1.14 to 3.45) and in those with a cumulative dosage greater than 28,000 mg (rate ratio=2.54; 1.05 to 6.14).

Results from the study were published in the British Medical Journal (2012; 344:e3645).

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