It seems medical research linking diabetes drug Actos to bladder cancer just keeps piling up. A new study from Canada, recently published in the Canadian Medical Association Journal, found that the common diabetes treatment may be involved in raising bladder cancer risks for users by as much as 22 percent.
The authors of the new study say that they still aren’t sure how or why pioglitazone, the drug in Actos, is linked with the higher cancer risk. Senior study author Jeffrey A. Johnson says that recent studies of the drug’s effects in animals show that Actos may cause crystals to form, which might then irritate the bladder and trigger the increased cancer risk.
Current studies show that, overall, people with type 2 diabetes have about a 40 percent higher risk of developing bladder cancer than other people. Doctors think this may be because people with this type of diabetes have increased levels of insulin, a chemical produced by the body to help digest food, in their bodies.
According to the National Institutes of Health, diabetes affects 25.8 million people in the U.S., or just over 8 percent of people. Type 2 diabetes is the most common form of diabetes in the U.S., and diabetes is responsible for $116 billion in medical costs in the U.S. each year.
We’ve written before about the growing evidence linking Actos to cancer dangers. The drug in Actos is also a part of diabetes medications sold under the names Actoplus Met, Actoplus Met XR, and Duetact. According to the Food and Drug Administration (FDA), 2.3 million people filled prescriptions for pioglitazone drugs in the first 10 months of 2010.
The findings from the Canadian study reinforce findings by an earlier French study and a five-year study by the FDA, which all found links between the Actos drug and higher risks of bladder cancer. The FDA has said that it will continue to monitor data from patients prescribed diabetes drugs with pioglitazone in them.
According to the FDA, people who’ve taken pioglitazone drugs–whether under the name Actos, or in another form like Duetact–should be aware of the increased bladder cancer risk, as well as potential symptoms of bladder cancer. Symptoms includepain in the lower back and abdomen, the appearance of blood or a red color in urine, pain while urinating, or an urgent need to urinate. Experts still don’t agree about how best to safeguard patients–France suspended the drug, and Germany recommended that doctors not prescribe it for any new diabetes cases. In the U.S., some doctors say they have stopped prescribing the drug. Others say they look at a patient’s overall background and cancer risk, and may still prescribe the drug if the risk of cancer seems low enough. For the millions of American patients taking the pioglitazone drug, however, this new study may just show that the risk is never low enough.