Metformin (Dimethylbiguanide) and Insulin Resistance in Women Completing Neoadjuvant and/or Adjuvant Cytotoxic Treatment of Stage I-III Breast Cancer
This phase III trial evaluates how often women develop insulin resistance and type-2 diabetes and compares metformin with usual care to usual care alone in treating insulin resistance in women with stage I-III breast cancer after chemotherapy. Insulin resistance occurs when cells stop responding to insulin and is a risk factor for developing diabetes and heart disease. Higher levels of insulin have been shown to be associated with aggressive breast cancer. Metformin hydrochloride decreases the amount of glucose (a type of sugar) released into the bloodstream from the liver and increases the body's use of the glucose. Metformin as well as standard of care diet and exercise education is known to lower blood sugar. However, chemotherapy may accelerate metabolic disorders, such as high blood sugar, and the impact of metformin in these breast cancer survivors is not known. Giving metformin with usual care may be more effective than usual care alone in preventing or reversing insulin resistance in women with stage I-III breast cancer after chemotherapy.
• Documented informed consent of the participant and/or legally authorized representative
• Agreement to allow lab draw of approximately 26 mL of blood (less than 3 tablespoons)
‣ To check blood counts, organ function and disease at baseline and 12 months
⁃ Clinical labs at baseline, 3 months, 6 months,12 months, and 24 months
⁃ Research labs at baseline, 6 months,12 months, and 24 months
• Age: ≥ 18 years
• Female sex assigned at birth
• Ability to read and understand English or Spanish for questionnaires
• Diagnosis of estrogen receptor (ER)-negative /HER2-wild type or -amplified invasive mammary carcinoma stages I-III
• Receive systemic treatment for breast cancer treatment
• Completed treatment for stage 1-3 breast cancer within 90 days to 5 years and are disease free
• Women who receive drugs for weight loss - e.g. semaglutide - prior to diagnosis are eligible for this protocol and can continue the drug during the intervention