The evidence linking long-term use of Actos, a drug widely prescribed to treat type 2 diabetes, to an increased risk of bladder cancer continues to mount. The latest news can be found in a study published in August 2012 in the Journal of the National Cancer Institute.
Researchers from the Perelman School of Medicine at the University of Pennsylvania warn that patients who take thiazolidinedione (TZDs) drugs — Avandia or Actos — for five or more years are two to three times more likely to develop bladder cancer than those who take other diabetes medications.
Thiazolidinedione Drugs Linked to Bladder Cancer
They analyzed data on 60,000 type 2 diabetes patients from The Health Improvement Network (THIN) database in the United Kingdom and focused on the differences between thiazolidinedione and sulfonylurea drugs. The authors concluded that 170 patients per 100,000 who take TZDs could develop bladder cancer. The number of patients prescribed sulfonylurea drugs who would be expected to have bladder cancer was only 60 per 100,000.
“Our study shows that doctors who care for patients with diabetes should be very aware of any bladder-related symptoms patients might be having, like blood in the urine, and take steps to further evaluate those issues,” said the study’s lead author, Dr. Ronac Mamtani.
This study, which was funded by the National Institutes of Health, is among the first to compare the risks of TZD drugs to those of sulfonylurea drugs, according to the University of Pennsylvania news release. It is not, however, the first to find a definitive association between Actos (pioglitazone) and bladder cancer.
Multiple Studies Link Actos to Bladder Cancer
A study that appeared in the Canadian Medical Association Journal in July 2012 asserted that taking Actos adds a 22 percent risk to the already elevated risk of bladder cancer that diabetes patients experience. Simply having the disease increases the risk by 40 percent. That means Actos patients are thought to have a 62 percent risk of developing bladder cancer.
The risks are so high that the Takeda Pharmacueticals drug has been banned in France and Germany as of June 2011. In the United States, the U.S. Food and Drug Administration (FDA) issued more stringent warnings in August 2011, based on a study by Kaiser Permanente Northern California. The agency stated that taking Actos for more than 12 months increases the patient’s risk of bladder cancer, and it further required medicines that contain pioglitazone to include the warning on their labels and inserts.
And still, millions of Actos prescriptions are written each year in the United States. That has led to thousands of lawsuits, many of which are consolidated in federal court in the Western District of Louisiana. The first trial is expected to start in November 2014.