The U.S. Food and Drug Administration (FDA) announced that use of pioglitazone (Actos) for the treatment of type 2 diabetes may increase bladder cancer risk. The group has accordingly updated labels on medication containing the drug.1

The FDA previously required manufacturers to include warnings about the potential risk for bladder cancer as of August 2011 based on interim results of a 10-year epidemiologic study of the drug, which has been approved to improve control of blood sugar with diet and exercise among adult patients with type 2 diabetes.

Additional studies of pioglitazone, however, have reported conflicting data on both the possible association with bladder cancer and whether treatment duration or dosage with the drug influenced risk.

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In the 5-year interim of the 10-year prospective study conducted by Takeda, which manufactures pioglitazone, researchers reported that they found no increased risk of bladder cancer among patients who were exposed to pioglitazone in contrast with those who were never exposed to the drug. Yet the risk of bladder had increased with higher dosage and longer treatment duration with pioglitazone.

The final 10-year study results included 1075 patients among 158,918 who were diagnosed with bladder cancer and had never been exposed to pioglitazone, as well as 186 patients among 34,181 who were diagnosed and were exposed to the drug at some point. They observed no increased risk for bladder cancer and had found weaker associations compared to the 5-year interim results.

In another study that evaluated 10,951 who underwent treatment with pioglitazone, 54 were found to have developed bladder cancer upon exposure to pioglitazone. The researchers also noted statistically significant trends for risk of bladder cancer with an increased duration and dosage of the drug.

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“Overall, we conclude that pioglitazone may be associated with an increased risk in urinary bladder cancer, and we have updated the drug labels to include information about these additional studies,” the FDA stated in the announcement.


  1. FDA Drug Safety Communication: Updated FDA review concludes that use of type 2 diabetes medicine pioglitazone may be linked to an increased risk of bladder cancer. FDA website. Updated December 12, 2016. Accessed December 14, 2016.