Lung cancer risk unaffected by metformin use in diabetes

(HealthDay)—Patients with type 2 diabetes who take metformin do not have a reduced risk of lung cancer, in contrast to previous observational studies, according to a study published online Aug. 24 in Diabetes Care.

To determine whether metformin use in type 2 diabetes is associated with the incidence of lung cancer, Brielan B. Smiechowski, from the Jewish General Hospital in Montreal, and colleagues analyzed data from 115,923 patients with type 2 diabetes newly treated with oral hypoglycemic agents.

The researchers found that 1,061 patients were diagnosed with lung cancer during follow-up. Based on matching each lung cancer case with up to 10 matched control subjects, metformin had no effect on the lung cancer rate (rate ratio, 0.94). Smoking status had no effect. No dose-response was noted based on number of prescriptions received, cumulative duration of use, and cumulative dose.

"Metformin use is not associated with a decreased risk of lung cancer in patients with type 2 diabetes," Smiechowski and colleagues conclude. "The decreased risk reported in other observational studies is likely due to bias from methodological shortcomings."