Metformin May Significantly Reduce Risk for Lymphedema after ALND

Rubin J, Pollack B, Coleman-Belin J, et al. Metformin Use and Risk of Breast Cancer-Related Lymphedema: A Retrospective Analysis. J Am Coll Surg. 2025, in press.

Lymphedema is a complication of axillary lymph node dissection (ALND) affecting more than 30% of patients who undergo ALND as a component of breast cancer treatment. Diabetes mellitus is associated with increased risk of lymphedema; available data suggest that treatment of diabetes with metformin reduces risk of lymphedema. The inflammatory response contributes to the risk for and severity of lymphedema; patients with diabetes have an increased inflammatory response, and this response is reduced in patients taking metformin.

This study was a retrospective analysis of data from a single cancer center. Patients (n = 4,882) were stratified as diabetic (n = 407) or non-diabetic and diabetic patients receiving metformin (n = 157) were identified.

Diagnosis of diabetes was a significant risk factor for lymphedema after ALND. After multivariable statistical analysis, metformin use was associated with a significant reduction in risk for lymphedema.

The authors recommended further research, including randomized trials in larger cohorts of patients to confirm the benefit of metformin.