Investigating the effects of metformin on growth factors involved in prostate cancer progression in prostate cancer patients

INTERVENTION: Metformin treatment over 6 weeks; oral tablets, dose ‐ 500 mg twice daily for the first week, followed by 1000 mg twice daily from the second week for 5 weeks. Adherence monitored by empty tablet packet return. No washout between metformin and placebo, as study visits will be at baseline and at the end of each treatment. CONDITION: Prostate cancer PRIMARY OUTCOME: A composite primary outcome is serum IGF‐1, IGF‐2, IGFBPs (IGFBP‐1 to 3) and bioactive IGF‐1 SECONDARY OUTCOME: Body composition, assessed by bioelectrical impedance spectroscopy Energy expenditure and substrate oxidation, assessed by indirect calorimetry Glucose tolerance, assessed by oral glucose tolerance test INCLUSION CRITERIA: (1) Age 50 to 80 years (2) ECOG equal or lower than 1 (3) Histologically confirmed prostate cancer of early or locally advanced stage, metastatic prostate cancer with bone involvement only (4) Stable treatment with ADT in the form of a GnRH agonist for more than 6 months (5) Able to understand and the willingness to sign a written informed consent document