For the third time in recent months, a new study has found that type 2 diabetics who take Actos face a higher risk of developing bladder cancer. The study, which is published in the Journal of the National Cancer Institute, found that patients taking thiazolidinediones face as high as a 3-fold increased risk of developing bladder cancer, compared to patients who use sulfonylurea drugs, another common class of type 2 diabetes medications.
As a class, thiazolidinediones account for up to 20 percent of the drugs prescribed to diabetics in the U.S. The thiazolidinedione drug class includes Actos, as well as Avandia. Few people use Avandia today because of its association with life-threatening heart side effects. But Actos ranks among the top selling type 2 diabetes treatments, with more than 15 million prescriptions written for the drug in the U.S. every year.
Actos’ possible association with bladder cancer has been a concern for several years now. On June 15, 2011, the U.S. Food & Drug Administration (FDA) issued a safety communication stating that use of Actos for more than one year may be associated with an increased risk of bladder cancer. That same month, the French and German governments decided to suspend sales of Actos in those countries after a separate study commissioned by French regulators demonstrated an increased risk of bladder cancer associated with Actos in people who took it the longest and at the highest cumulative dose. On July 12, 2011, Takeda Pharmaceuticals officially recalled Actos from the market in France.
For this new study, researchers at the Perelman School of Medicine at the University of Pennsylvania analyzed data on 60,000 type 2 diabetes patients from the Health Improvement Network (THIN) database in the U.K. The analysis showed that among patients taking either Actos or Avandia for five years, 170 patients per 100,000 would be expected to develop bladder cancer. Among patients taking a sulfonylurea drug, only 60 in 100,000 would be expected to develop the disease.
The findings are alarming, as people with type 2 diabetes are already more likely to develop bladder cancer compared to the general population.
“The fact that we have compared bladder cancer risk among patients taking each of those drugs provides essential information, because a safety warning on a drug is only useful to a doctor when they have knowledge of the same risks for an alternative drug,” lead author, Ronac Mamtani, MD, said.
“We believe our study will help doctors and their patients weigh the potential benefits and risks when selecting between different diabetes medications .”
This is the third study since May to confirm the association between Actos and bladder cancer. In May, a Canadian study published in the British Medical Journal found that taking Actos for two years doubled the risk of bladder cancer. In July, a study published in the Canadian Medical Association Journal (CMAJ) found a 22 percent increased risk of bladder cancer when taking Actos.