A Trial of Standard Chemotherapy With Metformin (vs Placebo) in Women With Metastatic Breast Cancer

Exclusion Criteria

• •More than one previous line(s) of chemotherapy for metastatic disease - if prior chemotherapy has been administered, the last date of treatment must have been given at least 3 weeks prior to registration \[any adjuvant systemic treatment is acceptable\]
• •If prior hormone therapy (as adjuvant or metastatic therapy) has been administered, it must have been stopped at least 3 weeks prior to registration
• •Radiotherapy to a target or non target lesion within 4 weeks of registration
• •Known CNS metastases
• •History of cardiac failure
• •Known hypersensitivity or allergy to metformin
• •History of or known diabetes or baseline fasting glucose ≥ 7.0 mmol/L
• •History of lactic or other metabolic acidosis
• •Use of metformin within 3 months of registration
• •Current or planned pregnancy or lactation in women of child-bearing potential. Patients of childbearing potential must have a negative serum pregnancy test.
• •Fertile patients must agree to use an effective method of contraception while on study treatment; which could include IUD, condoms or other barrier methods of birth control
• •Habitual alcohol intake of more than three drinks daily
• •Concurrent use of any biguanide medication (other than metformin as a study medication)
• •Patients with ≥ grade 2 diarrhea at baseline, malabsorption syndrome or unable to swallow oral medication
• •Previous or concurrent malignancies, except non-melanoma skin cancers, unless curatively treated and with no evidence of recurrence for ≥ 5 years.
• •Use of any investigational agent within 28 days prior to registration.