Can metformin improve lung cancer survival for people living with overweight or obesity?

New research in the United States suggests that metformin could enhance outcomes for people with lung cancer living with overweight and obesity.

Published in the Journal of the National Cancer Institute, the study highlights metformin’s potential to boost immunotherapy results and improve recurrence-free survival in this high-risk group.

Previous studies on metformin’s role in lung cancer treatment have yielded mixed results, partly because they did not specifically examine patients living with obesity or high body mass index (BMI). With obesity affecting 40.3 per cent of U.S. adults, according to the Centers for Diesese Control and Prevention (CDC), this focus is critical for developing tailored cancer care solutions.

The Roswell Park team, led by Sai Yendamuri, M.D., M.B.A., chair of thoracic surgery, narrowed their study to individuals with non-small cell lung cancer who had a BMI of 25 or higher. The findings suggest that the anticancer benefits of metformin are most significant in the context of obesity.

Key findings included metformin use reduced the risk of cancer recurrence by nearly 50 per cent (hazard ratio [HR] of 0.47).

Additionally, in a group of patients receiving immunotherapy, those living with obesity or overweight experienced a 40 per cent improvement in progression-free survival (HR of 0.60).

In animal models, metformin slowed tumour growth and reversed obesity-related immune suppression. When combined with immunotherapy, it further enhanced tumour control, suggesting that metformin shifts the balance toward immune activation and tumour destruction.

The research team is now conducting a phase 2 clinical trial to explore metformin’s potential for preventing lung cancer in high-risk individuals living with overweight or obesity. Funded by the National Cancer Institute, this trial is taking place at Roswell Park and two other centres in the U.S. and Canada.

“Metformin has been used for 30 years and has a long record of safety,” said Dr. Yendamuri. “If we can repurpose it to fight cancer, that’s very exciting.”