Study: Diabetes drugs may be associated with increased bladder cancer risk

NEW YORK — A drug commonly used to treat diabetes may be associated with an increased risk of bladder cancer, according to a new study published in the Canadian Medical Association Journal.

The researchers — who noted that Type 2 diabetics are at an increased risk of developing cancers, including a 40% increased risk of bladder cancer — conducted a systematic review and meta-analysis to evaluate the risk of bladder cancer among adults with Type 2 diabetes taking thiazolidinediones. The systematic review and meta-analysis of randomized controlled trials and observational studies involved more than 2.6 million patients. Among them, 3,643 had newly diagnosed bladder cancer.

"We observed an increased risk of bladder cancer associated with the use of thiazolidinediones," said Jeffrey Johnson of the School of Public Health at the University of Alberta. "In particular, use of pioglitazone was associated with an increased risk of bladder cancer based on a pooled estimate from three cohort studies involving more than 1.7 million individuals."

The researchers also looked at a possible association with rosiglitazone (another type of thiazolidinedione) but did not see an effect.

"Although the absolute risk of bladder cancer associated with pioglitazone was small, other evidence-based treatments for Type 2 diabetes may be equally effective and do not carry a risk of cancer," conclude the authors. "This study quantifies the association between pioglitazone use and bladder cancer and may help inform decisions around safer use of pioglitazone in individuals with Type 2 diabetes."

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