* Two years use of Actos doubles risk of bladder cancer
* Absolute risk still low, study finds
LONDON May 31 Taking Takeda Pharmaceutical's diabetes drug Actos for more than two years doubles the risk of bladder cancer, although in absolute terms the risk is still low, researchers said on Thursday.
A study by Canadian researchers, published online by the British Medical Journal, quantified the risk by analysing the records of more than 115,000 British patients newly treated with diabetes drugs between 1988 and 2009.
They found that Actos use of two years or more was associated with 88 extra cases of bladder cancer per 100,000 person years. This rose to 137 extra cases among patients who had taken more than 28,000 milligrams of the drug.
Worries about a link between Actos and bladder cancer hit the headlines last year when U.S. and European regulators issued warnings about the risk, while deciding to keep the medicine on the market. The warnings hit sales of the drug.
In an editorial accompanying the new study, Dominique Hillaire-Buys and Jean-Luc Faillie from the Department of Medical Pharmacology and Toxicology in Montpellier, France, said the research would prompt questions about future use of Actos, which is known generically as pioglitazone.
"Prescribers who are ultimately responsible for therapeutic choices can legitimately question whether the benefit-risk ratio of pioglitazone is still acceptable for their patients with diabetes," they said.
Actos had peak sales of nearly $5 billion in the year to March 2010, but revenue has since declined, and Takeda faces generic competition as the drug's patents expire.
Takeda has previously said it is confident of the benefits of Actos in treating type 2 diabetes, and it continues to monitor the safety of all its medicines.
Actos belongs to the same drug class as GlaxoSmithKline's Avandia, which has been linked to heart problems but not bladder cancer.