No Cancer Risk Found for Diabetes Rx

Pioglitazone and rosiglitazone did not raise bladder cancer risk, despite past research that suggested they might

(RxWiki News) Worried about the health effects of the medications you take? There's likely no need to worry about two diabetes medications once thought to increase the risk of cancer.

The authors of a new study found that pioglitazone (brand name Actos) and rosiglitazone (brand name Avandia) did not lead to an increased risk of bladder cancer — despite past studies that suggested they did. Also, long exposure to the diabetes medications didn't lead to a risk for cancer.

"In summary, our large international analysis does not support a causal effect of pioglitazone on bladder cancer, thus contradicting previous studies deemed to have proven this relationship," wrote the study authors, led by Samira Bell, MD of the Renal Unit of Ninewells Hospital and Medical School in Dundee, the UK.

People with type 2 diabetes do not respond properly to insulin. Insulin is a hormone that regulates blood sugar and metabolism. Pioglitazone and rosiglitazone increase the body's ability to respond to insulin.

The two medications also act similarly to bladder cancer tumors in cells of the urinary tract, Dr. Bell and colleagues wrote. Past studies have tied the medications to a risk of bladder cancer.

In this study, Dr. Bell and team used patient data from more than 1 million people with type 2 diabetes from many countries, including the US, Canada and the UK. Patients from 566 medical practices were included.

These researchers followed up with the patients for about four to seven years to examine the effects of pioglitazone and rosiglitazone on bladder cancer. They found that there was no additional risk of bladder cancer among diabetes patients who took the medications — compared to those who did not take them.

Also, Dr. Bell and team found that the risk of bladder cancer did not increase as people took the medications for longer amounts of time.

The authors noted that past studies on these medications were weaker than the current one because they did not draw data from a large, international pool of patients.

Dr. Bell and colleagues concluded that pioglitazone and rosiglitazone did not lead to higher rates of bladder cancer.

This study was published Dec. 3 in Diabetologia.

The European Foundation for the Study of Diabetes funded the study. Some of the authors disclosed financial ties to pharmaceutical companies like Pfizer and Novartis.

Review Date: 
December 3, 2014