May 31, 2012 -- The diabetes drug Actos (pioglitazone) already carries a warning about its risk for bladder cancer, and now new research suggests that this risk may be greater than previously believed.
According to the new study, use of Actos for more than two years doubles the risk of bladder cancer. Still, the overall risk of any one person developing bladder cancer by taking Actos is very small.
"Patients with type 2 diabetes and their physicians need to be fully aware of the potential association between Actos and bladder cancer," says researcher Laurent Azoulay, PhD. He is an epidemiologist at Lady Davis Institute of Jewish General Hospital in Montreal, Quebec, Canada. "Certainly, this drug should not be used in patients with a history of bladder cancer and those with other bladder conditions."
The findings appear in the journal BMJ.
Overall Risk of Bladder Cancer Still Low Among Actos Users
Bladder cancer is relatively uncommon. In the U.S., about 73,510 new cases of bladder cancer will be diagnosed in 2012, according to the American Cancer Society. "The decision to continue using [Actos] or starting it should be discussed with the physician, who will be able to carefully assess the whether the benefits outweigh the potential risks for a given patient."
The researchers analyzed data on more than 115,000 people who were treated with diabetes drugs from 1988 to 2009. Overall, 470 people were diagnosed with bladder cancer during about 4.6 years of follow-up. These individuals were compared with healthy people.
People who had ever taken Actos had an 83% increased risk of bladder cancer, the researchers found. This risk increased when individuals took the diabetes drug for more than two years and when they took higher doses of it. There was no increased risk was seen for Avandia (rosiglitazone), another diabetes drug in this class.
Actos Manufacturer Responds
The manufacturer of Actos, Takeda Pharmaceuticals, has not reviewed the new study, but Elissa J. Johnsen, a spokesperson for Takeda in Deerfield, Ill., did supply WebMD with the following statement:
"Takeda is confident in the therapeutic benefits of Actos and its importance as a treatment for type 2 diabetes. As a science and evidence-based company, Takeda firmly stands behind the substantial data available confirming the positive risk/benefit profile of Actos, which includes more than 12 years of clinical and patient experience with the product."
"As a company, Takeda is committed to ongoing clinical research to understand and investigate potential safety concerns, and is currently supporting several ongoing studies, including a 10-year epidemiological study, investigating the potential relationship between Actos and bladder cancer."
Making the Decision to Take Actos
Spyros Mezitis, MD, says that it comes down to balancing the risks of bladder cancer with other perceived benefits of this medication. He is an endocrinologist at Lenox Hill Hospital in New York.
"We need to be careful when starting patients on Actos, and we should be checking for bladder cancer in urine samples among the ones who are already taking it," he tells WebMD. "The risk seems to be dose and duration dependent," meaning that higher doses of the drug taken for longer periods of time confer a greater risk for bladder cancer.
The Actos label states that you should not take the drug if you are receiving treatment for bladder cancer. It also warns people to tell their doctor right away if they develop any bladder cancer symptoms including blood or a red color in urine, increased need to urinate, and pain during urination.
There are other diabetes drugs available, Mezitis says.
Actos has been banned in France and Germany.
In an editorial accompanying the study, Dominique Hillaire-Buys and Jean-Luc Faillie from the Department of Medical Pharmacology and Toxicology in Montpellier, France, write: "It can confidently be assumed that [Actos] increases the risk of bladder cancer. It also seems that this association could have been predicted earlier."