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Diabetes Drugs Prescribed Raises Risk of Bladder Cancer

PHILADELPHIA  — A popular class of diabetes drugs increases patients’ risk of bladder cancer,  according to a new study published online this month in the Journal of the National Cancer Institute.  Researchers from the Perelman School of Medicine at the University of  Pennsylvania  found that patients taking  thiazolidinedione (TZDs) drugs – which account for up to 20 percent of the  drugs prescribed to diabetics in the United States — are two to three times  more likely to develop bladder cancer than those who took a sulfonylurea drug,  another common class of medications for diabetes.

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The  authors say the findings are especially important since diabetic patients are  known to already be at a slightly increased risk of this type of cancer as  compared to the general population, in which about 30 in 100,000 people  develop bladder cancer. Among diabetes patients overall, the incidence of this  cancer is typically about 40 out of 100,000.

The  authors of the new study analyzed 60,000 Type 2 diabetes patients from the  Health Improvement Network (THIN) database in the United Kingdom. They found  that patients treated with the TZD drugs pioglitazone (Actos) or rosiglitzaone  (Avandia) for five or more years had a two-to-three-fold increase in risk of  developing bladder cancer when compared to those who took sulfonylurea drugs.  Among patients taking TZDs for that length of time, the team’s analysis  indicates that 170 patients per 100,000 would be expected to develop the  disease. About 60 in 100,000 of those who take sulfonylurea drugs – such as glipizide  (Glucotrol) — would be expected to develop bladder cancer.

“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,” said the study’s lead author, Ronac Mamtani, MD, an instructor in the  division of Hematology-Oncology in Penn’s Abramson Cancer Center. “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.”

Though  most patients in the United States no longer take Avandia since it was linked  to severe cardiovascular problems, Actos is the ninth most commonly prescribed  drug in the nation, accounting for some 15 million prescriptions each year. The  drug is a common choice when Type 2 diabetes patients’ illnesses can no longer  be controlled with the first-line diabetes drug Metformin.

Based  on previous data examining safety risks among patients taking Actos, the FDA  has already warned that it may be associated with a risk of bladder cancer, and  France and Germany have removed the drug from their markets. The new findings  add to mounting evidence against the entire class of TZDs, as one of the first  studies examining this type of risk among people taking both types of TZDs and among  those taking 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,” Mamtani says. “We believe our study will help doctors and  their patients weigh the potential benefits and risks when selecting between  different diabetes medication.”

The study was  funded by the National Institutes of Health (T32-CA009679-20, UL1-RR024134,  and K24-DK078228).


Penn Medicine is one of the world’s  leading academic medical centers, dedicated to the related missions of medical  education, biomedical research, and excellence in patient care. Penn Medicine  consists of the Raymond and Ruth Perelman  School of Medicine at the University of Pennsylvania (founded in 1765 as  the nation’s first medical school) and the University of Pennsylvania Health System,  which together form a $4.3 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 16 years, according to U.S. News & World Report’s survey of research-oriented medical schools. The  School is consistently among the nation’s top recipients of funding from the  National Institutes of Health, with $398 million awarded in the 2012 fiscal  year.

The University of Pennsylvania Health System’s patient  care facilities include: The Hospital of the University of Pennsylvania —  recognized as one of the nation’s top “Honor Roll” hospitals by U.S.  News & World Report; Penn Presbyterian Medical Center; and  Pennsylvania Hospital — the nation’s first hospital, founded in 1751. Penn  Medicine also includes additional patient care facilities and services  throughout the Philadelphia region.

Penn Medicine is committed to improving lives and health  through a variety of community-based programs and activities. In fiscal year  2012, Penn Medicine provided $827 million to benefit our community.