Use of Metformin to reduce serum level of Testosterone and improve the metabolic picture in women treated for breast cancer

INTERVENTION: Trade Name: METFORMINA MERCK Pharmaceutical Form: Tablet INN or Proposed INN: Metformin Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 1000‐ CONDITION: Menopausal women on treatment for BC, with higher risk of recurrence due to augmented level of T ; MedDRA version: 6.1 Level: PT Classification code 10006187 PRIMARY OUTCOME: Main Objective: Relatively high level of Testosterone, due to insulin resistance, are asociated with higher risk of breast cancer (BC) and even of recurrences of BC. The main objective is to define the smallest dose of Metformin able to reduce augmented serum level of T and to modify other metabolic parameters in menopausal women on treatment for BC (randomised comparison of two doses) Primary end point(s): To define the smallest dose of Metformin able to reduce augmented serum level of Testosterone in women on treatment for breast cancer Secondary Objective: To define the toleralibity of Metformin 1000 ‐ 1500 mg/d in menopausal women on treatment for BC INCLUSION CRITERIA: Women with previous surgery for BC, in spontaneous menopause, aged less than 70 years, with serum T level above the median, in one of the following conditions (characterized by endocrine and metabolic stabilization): 1) At least 6 months from surgery in absence of systemic treatment; 2) In therapy with Tamoxifen since at least 6 months with the perspective of prosecute it for at least another year; 3) At least 6 months from the end of chemiotherapy. Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range