The findings of new research raise questions about the potential risk of bladder cancer in connection with the diabetes drugs Actos and Avandia.
In a study published in the medical journal Diabetologia (PDF) on December 3, researchers from the University of Dundee in the U.K. and from the International Diabetes and Cancer Researcher Collaboration indicate that they found no evidence that using Actos or Avandia increases the risk of being diagnosed with bladder cancer.
The findings contradict a number of previous studies that have found a link between side effects of Actos and bladder cancer, which resulted in the FDA forcing new warnings to be placed on the popular diabetes drug in 2011.
In addition, the study comes as thousands of former users of the drug who have been diagnosed with bladder cancer are continuing to pursue Actos lawsuits against Takeda Pharmaceuticals, with several juries returning multi-million dollar awards after finding that the drug maker actively concealed the risk from consumers and the medical community.
Researchers in this latest study looked at prescription, cancer and mortality data involving people from the U.K., Canada and Europe. In total, 5.9 million person-years worth of data were collected on more than 1 million people.
“The rates of bladder cancer observed in our study were in keeping with the international statistics on population rates of bladder cancer,” the researchers concluded. “Observational studies examining the risk of bladder cancer and [Actos] have yielded contradictory results. These studies varied in size and design, but all were prone to inappropriate causal inference and potential confounding. Most include a small number of exposed cases.”
The researchers said that the contradictions between the studies can only be resolved by a larger study, with a longer follow-up of exposed persons and methods that minimize allocation bias.
Concerns about the Actos bladder cancer risk first emerged in 2010, following a study by French insurers that found increased rates of tumors among users of the diabetes drug.
In August 2011, the FDA required new bladder cancer warnings to be placed on the medication, indicating that individuals who use the diabetes drug for more than a year may face an increased risk.
Earlier this year a jury handed down a $9 billion punitive damages verdict in the first bellwether test trial to take place in federal court. U.S. District Judge Rebecca Doherty later reduced the punitive damages to $37 million, but lamented in her opinion that the Supreme Court needs to update rules on what is considered excessive in order to effectively deter large corporations the type of bad behavior exhibited by Takeda.
More recently, state court juries in Pennsylvania and West Virginia have reached similar findings. In October, a Philadelphia jury awarded $2 million in damages over bladder cancer from Actos. The next month, a West Virginia jury awarded $155,000 in damages after finding that Takeda destroyed evidence linking Actos to bladder cancer.