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17-04-2011 | Diabetes | Article

Long-term pioglitazone use linked to bladder cancer risk


Free abstract

MedWire News: Use of pioglitazone for over 2 years may increase a patient's risk for developing bladder cancer, although only weakly, suggest study results.

However, the researchers found that shorter-term use did not significantly increase bladder cancer risk in the same patient group.

James Lewis (University of Pennsylvania, Philadelphia, USA) and colleagues assessed whether pioglitazone use increases the risk for developing bladder cancer using data from the Kaiser Permanente Northern California Diabetes registry on 30,173 Type 2 diabetes patients who were treated with this drug.

Among at total of 193,099 patients in the registry, 90 pioglitazone users developed bladder cancer compared with 791 non-pioglitazone users.

Ever-use of pioglitazone did not significantly increase the risk for bladder cancer, with similar results in men and women.

However, patients who had been treated with pioglitazone for over 2 years had a significant 1.4-fold increased risk for developing bladder cancer compared with non-users.

In addition, results from a post hoc analysis suggest that the risk for bladder cancer is likely to increase further with even longer pioglitazone exposure periods.

"It is possible that any increased risk of bladder cancer observed with pioglitazone could be attributed to other diabetes medications that reduce the risk of bladder cancer," say Lewis et al.

"However, we did not observe any association between ever use of other diabetes medications and bladder cancer risk."

Additional follow-up is planned to explore the link between long-term pioglitazone use and bladder cancer risk, conclude the investigators in the journal Diabetes Care.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Helen Albert