Breast Cancer Survivors on GLP-1 Drugs Had About a Third the Rate of Coded Lymphedema After Mastectomy or Lymph Node Surgery
Researchers at Jefferson Einstein Philadelphia Hospital reported in Supportive Care in Cancer on October 27, 2026 a TriNetX study of 61,630 propensity-matched adults with breast cancer who had a mastectomy or underarm lymph node procedure. Coded postmastectomy lymphedema, arm swelling caused by damaged lymph drainage, was recorded in 0.88% of GLP-1 users versus 2.58% of nonusers over up to 650 days (hazard ratio 0.37), an absolute difference of 1.7 percentage points. The study relied on diagnosis codes and cannot show that the drugs prevented lymphedema.