New research published in the Journal of the National Cancer Institute has found that a popular class of diabetes drug increases people’s risk of developing bladder cancer.
According to researchers from the Perelman School of Medicine at the University of Pennsylvania, the drug that accounts for up to 20% of the medication prescribed to diabetics in the U.S., thiazolidinedione (TZDs), gives patients a 2 to 3 times greater likelihood of developing bladder cancer than those taking a sulfonylurea drug, another common class of medication for diabetics.
Diabetes patients are already known to have a slightly greater chance of developing this cancer as compared to the general population, which the authors suggest makes this finding especially important. About 40 out of 100,00 diabetics typically eventually develop cancer of the bladder, versus 30 in 100,000 out of the general population.
Sixty thousand type 2 diabetics from the Health Improvement Network (THIN) database in the United Kingdom were observed in the study.
Authors found that people treated with the TZD drugs, pioglitazone (Actos) or rosiglitzaone (Avandia), had a 2 to 3 fold increase in the risk of bladder cancer after 5 or more years taking the drug, as opposed to those who took sulfonylurea drugs, like glipizide (Glucotrol).
The experts’ analysis showed that 170 patients per 100,000 taking TZDs, for 5 or more years, were expected to develop this disease. For those taking sulfonylurea drugs, about 60 in 100,000 would develop bladder cancer.
Ronac Mamtani, MD, the study’s lead author, an instructor in the division of Hematology-Oncology in Penn’s Abramson Cancer Center, explained:
“Diabetes is one the most common chronic diseases worldwide, affecting 285 million people. There are many factors clinicians must weigh in deciding which drug to use to control a patient’s diabetes, and these new data provide important information to include in that decision-making process. 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.”
Ever since Avandia became linked to severe cardiovascular problems, the majority of people in the United States no longer take it.
However, about 15 million prescriptions are written for Actos each year; it is the 9th most popular prescribed drug in the nation. This drug is usually chosen when Metformin, the first-line diabetes drug, can no longer control the illnesses of type 2 diabetes patients.
Germany and France have already taken Actos off the market, and the FDA has even warned that it may be associated with a risk of bladder cancer because of evidence in previous research.
This new finding should rule out the entire class of TZDs, as this was one of the first studies to analyze the risk of bladder cancer among patients taking either TZDs or sulfonylurea drugs.
“The risk does seem to be common among both drugs in the TZD class, and 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. We believe our study will help doctors and their patients weigh the potential benefits and risks when selecting between different diabetes medication.”
Written by Sarah Glynn