Type 2 diabetes drug pioglitazone not linked to bladder cancer

Contrary to previous suggestions, the type 2 diabetes drug pioglitazone is not linked to bladder cancer, according to new research.
However, the new study, which was conducted by researchers from the University of Pennsylvania, did find a possible increased risk of prostate and pancreatic cancer.
Pioglitazone (brand name Actos in the UK) aids blood sugar control by encouraging the body to use insulin more effectively. Previous research has linked pioglitazone to a higher risk of bladder cancer, but this study suggests that such links are false.
A study by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) found a 1.4-fold increase in risk of bladder cancer for patients taking pioglitazone for more than two years.
This study analysed the data of 193,099 people with diabetes, all of whom were older than 40. An accompanying study examined the data of 236,507 people with diabetes, and tested for an increased risk of other cancers.
34,181 patients from the first group received pioglitazone. 1,261 of them developed bladder cancer. This represented no risk increase of bladder cancer.
The researchers did, however, find a link between pioglitazone use and a higher risk of prostate and pancreatic cancer, but further studies are needed to confirm this association.
The researchers suggested that the increased risk of pancreatic cancer – which is also associated with a number of other diabetes medications – might be due to reverse causality; early stages of pancreatic cancer often manifest as hyperglycemia, so it is possibly the pancreatic cancer that causes the need for diabetes medication, rather than the other way around.
“The increased prostate and pancreatic cancer risks associated with ever use of pioglitazone merit further investigation to assess whether the observed associations are causal or due to chance, residual confounding, or reverse causality.”
The findings were published in the Journal of the American Medical Association.