Presurgical trial of metformin in overweight and obese patients with newly diagnosed breast cancer.

ABSTRACT

INTRODUCTION: We conducted a presurgical trial to assess the tissue-related effects of metformin in overweight/obese breast cancer (BC) patients. METHODS: Metformin 1,500 mg daily was administered to 35 nondiabetics with stage 0-III BC, body mass index (BMI) ≥ 25 kg/m(2). The primary endpoint was tumor proliferation change (i.e., ki-67). Tumor proliferation change was compared to untreated historical controls, matched by age, BMI, and stage. RESULTS: There was no reduction in ln(ki-67) after metformin (p = .98) or compared to controls (p = .47). There was a significant reduction in BMI, cholesterol, and leptin. CONCLUSION: Despite no proliferation changes, we observed reductions in other relevant biomarkers.