New evidence has revealed that metformin, a popular diabetes medication thought to inhibit the progression of lung cancer, actually has a nonsignificant effect on mortality in patients with lung cancer.
Retrospective studies had suggested that adding metformin to treatment plans for patients with diabetes and cancer could inhibit disease progression. In particular, a study published in the American Journal of Respiratory and Critical Care Medicine found that patients with non-small cell lung cancer and diabetes who were treated with metformin had a median survival of 5 months, compared with 3 months in patients not taking the drug. These results led some to suspect that metformin could have cancer-inhibiting properties.
In a study published online in the journal Lung Cancer, researchers conducted a population-based study to determine whether metformin is associated with a reduced risk of lung cancer-specific mortality in a larger sample of patients. Newly diagnosed patients with lung cancer who also had diabetes were identified using the English National Data Repository, the Office of National Statistics mortality data, and the UK Clinical Practice Research Datalink prescriptions and diagnosis records.
In 533 patients who received metformin after diagnosis, there was only a weak, non-significant relationship between use of metformin and cancer-related mortality. In a second analysis of 1350 patients who had been receiving metformin prior to cancer diagnosis, there was no association between the drug and a reduction in lung cancer mortality.
In addition, researchers looked at the use of other diabetes medications, such as sulfonylureas, insulin, and thiazolidinediones, taken either before or after diagnosis of lung cancer; no significant associations between these drugs and lung cancer-specific mortality were found.
Authors of the study concluded: “Overall, the results from this population-based study provide little evidence of a protective association between metformin use and cancer mortality in lung cancer patients.”
