Diabetes Drug Found to Lower Lung Cancer Risk in Non-Smokers

Diabetics who took metformin saw a decreased chance of developing adenocarcinoma.

Non-smokers who took the diabetes drug metformin had a decreased chance of developing lung cancer in a recent study.

The study, published recently in Cancer Prevention Research, sought to evaluate prior research that found conflicting evidence surrounding the ability of metformin to prevent cancer.

The researchers utilized a retrospective cohort study that included 47,351 diabetic patients (54% male), who were 40 years or older, and who had completed a health-related survey between 1994 and 1996. Data on diabetes medications were compiled from electronic pharmacy records.

Approximately 46% of patients filled 2 or more metformin prescriptions within a 6-month period. Over 15 years of follow-up, a total of 747 patients were diagnosed with lung cancer. Of these patients, 80 were non-smokers and 203 were current smokers.

The drug was not associated with a lower overall risk of lung cancer, but the risk was 43% lower in diabetic patients who never smoked, however the risk apparently decreased with longer use. Non-smokers who used metformin for 5 years or more had a 52% reduced risk for lung cancer, but the finding was not statistically significant.

The use of metformin for 5 years or more was associated with a 31% decreased adenocarcinoma risk.

"Metformin use was not associated with lung cancer risk when we looked at all patients with diabetes,” researcher Lori Sakoda, PhD, MPH, said in a press release. “However, our results suggest that risk might differ by smoking history, with metformin decreasing risk among nonsmokers and increasing risk among current smokers. Our results suggesting that the risk associated with metformin might differ by smoking history were unexpected. Additional large, well-conducted studies are needed to clarify whether metformin may be used to prevent lung or other cancers, particularly in specific subpopulations, such as nonsmokers."