The U.S. Food and Drug Administration is reviewing data suggesting a possible link between the diabetes medication Actos and bladder cancer.
The agency says five-year results from a study show patients taking Actos the longest had higher risk of bladder cancer. The drug's manufacturer Japan's Takeda Pharmaceuticals is conducting the study, which is scheduled to run 10 years.
"The agency has not concluded that Actos increases the risk of bladder cancer," the agency said in a statement.
Sales of Actos have surged in recent years because it is seen as a safer alternative to GlaxoSmithKline's diabetes drug Avandia. The FDA is considering whether to withdraw Avandia because of potential heart risks. The drugs work similarly to control blood sugar.
