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Diabetes Drug Actos Increases Bladder Cancer Risk

Diabetes drug increases bladder cancer risk

Two years ago, in September 2010, the Food and Drug Administration (FDA) announced that it was going to investigate a possible link between the diabetes drug Actos (pioglitazone) and an increased risk of bladder cancer. Now new research from the University of Pennsylvania shows a twofold to threefold increased risk of bladder cancer associated with long-term use of Actos.

Actos is often prescribed for diabetes

Actos is in a drug class known as thiazolidinedione (TZD), which works by reducing insulin resistance. The drug was approved in 1999 by the FDA for glycemic control in adults who have type 2 diabetes. Another TZD, Avandia (rosiglitazone) was recalled in Europe and had its sales restricted in the United States after it was linked with heart problems.

Although it's known that people with diabetes have a slightly greater risk of developing bladder cancer when compared with the general population, a research team from the Perelman School of Medicine at the University of Penn found that people with diabetes who took Actos for five years or longer had a much greater risk than did patients who took another common drug for diabetes.

The retrospective cohort study involved 18,459 patients who started treatment with a TZD and 41,396 who began with a sulfonylurea between July 1, 2000 and August 31, 2010. Sulfonylureas stimulate beta cells to produce more insulin, and the most prescribed include glipizide, glyburide, and glimepiride.

Analysis of the data revealed that 170 patients per 100,000 who took TZDs for at least five years were expected to develop bladder cancer compared with 60 patients per 100,000 among those taking sulfonylurea drugs.

According to the latest figures from Drugs.com, Actos ranked 21st in pharmaceutical sales in the United States in 2012, and sales have been declining. Actos has already been removed from the marketplace in France and Germany.

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In July 2012, GlaxoSmithKline, the makers of Avandia, plead guilty to misdemeanor criminal charges related, in part, to failing to provide safety warnings to the FDA concerning possible heart risks associated with use of the diabetes drug. Although the drug is still available in the US, it is rarely prescribed.

Ronac Mamtani, MD, the study's lead author and an instructor at the University of Penn's Abramson Cancer Center, noted that "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."

More about bladder cancer

Other symptoms of bladder cancer may include feeling an urgent need to empty the bladder, straining to empty the bladder, experiencing pain when emptying the bladder, and needing to empty the bladder more frequently.

The National Cancer Institute estimates 73,510 new cases of bladder cancer will be diagnosed in 2012 in the United States, and that 14,880 people will die of the disease. Risk factors for bladder cancer include smoking (the most important risk factor), exposure to chemicals at work (e.g., workers in rubber, chemical, metal, textile, and leather industries), treatment with certain cancer drugs and/or radiation therapy, exposure to arsenic, and family history of the disease.

Mamtani concluded that "our study will help doctors and their patients weigh the potential benefits and risks when selecting between different diabetes medication." Patients who take Actos should talk to their doctor about the risk of bladder cancer and switching to another diabetes drug.

Mamtani R et al. Association between longer therapy with thiazolidinediones and risk of bladder cancer: a cohort study. Journal of the National Cancer Institute 2012 Aug 9. doi:10.1093/jnci/djs328

Image: Wikimedia Commons