Diabetes drug reduces lung cancer risk in non-smokers

Whether or not the diabetes drug metformin lowers the risk of cancer is contested from a scientific point of view. A retrospective study carried out in the USA now indicates that the drug may lower the risk of lung cancer in non-smoking diabetics. The results were published in «Cancer Prevention Research».

Researchers from the Kaiser Permanente Division of Research in Oakland (California) analysed the data of 47,351 diabetics aged 40 or older. 46 per cent of them had taken metformin at some point in time (defined as those who filled at least two prescriptions within half a year).

During the 15-year observational period, 747 participants were diagnosed with lung cancer. Overall, the scientists found no association with lung cancer risk and metformin use. However, if the participants were divided according to their smoking status, it showed that the drug lowered the likelihood of non-smokers developing the disease. In concrete terms, it was 43 per cent lower. Using the drug longer – for more than five years – even reduced the risk further, namely by 52 per cent.

Metformin evidently reduces the risk for non-smoking diabetics, but it increases the risk for diabetics who smoke, said study author Lori Sakoda. That the risk might differ by smoking history was unexpected. Further studies for clarification were needed, she said.