Pioglitazone Linked With an Increased Risk of Bladder Cancer
Pioglitazone, a drug commonly prescribed for the treatment of type 2 diabetes, is linked with an increased risk of bladder cancer, according to a population-based cohort study involving nearly 146,000 individuals receiving treatment with antidiabetic drugs.
The study, published online March 30 in The British Medical Journal (BMJ), involved patients treated at general practices that contributed data to the United Kingdom Clinical Practice Research Datalink.
Investigators identified patients who initiated use of a new antidiabetic drug class between January 1, 2000, and July 31, 2013, and continued treatment for at least 1 year. For patients who initiated pioglitazone, a drug in the thiazolidinedione class, they estimated whether bladder cancer incidence was associated with pioglitazone use overall, with cumulative duration of use, or with cumulative drug dose. Similar analyses were conducted for rosiglitazone, another drug in the thiazolidinedione class that is not known to increase the risk of bladder cancer.
The data included nearly 690,000 person-years of follow-up. A total of 622 patients were newly diagnosed with bladder cancer, for a rate of roughly 90 per 100,000 person-years.
People who took pioglitazone were 63% more likely to develop bladder cancer than those who took antidiabetic medications other than thiazolidinediones (121 vs 89 per 100,000 person-years). In contrast, rosiglitazone was not linked with an increased risk of bladder cancer (86 per 100,000 person years). Additionally, duration of use and drug dose were associated with bladder cancer risk for those who took pioglitazone but not for those who took rosiglitazone.
The study’s authors wrote that the link between pioglitazone and bladder cancer has been controversial due to contradictory findings, but their results suggest that “the association observed…is likely to be a drug-specific and not a class effect.”
An accompanying editorial published in BMJ agreed with the authors’ observations, adding that the work confirms the results from most prior studies.
Reference
Montori VM. Selecting the right drug treatment for adults with type 2 diabetes. BMJ. 2016;352:i1663.
