Bicalutamide With or Without Metformin for Biochemical Recurrence in Overweight or Obese Prostate Cancer Patients

Inclusion Criteria: Ability to understand and the willingness to sign a written informed consent Male 18 years or older Histologically or cytologically confirmed diagnosis of prostate cancer Patient must have had previous treatment with definitive surgery or radiation therapy or cryoablation Patient may have prior salvage therapy (surgery, radiation or other local ablative procedures) within 6 months prior to randomization if the intent was for cure.Prophylactic radiotherapy to prevent gynecomastia within 4 weeks prior to randomization is allowed BMI \> 25 at study entry Patient may have had prior neoadjuvant and/or adjuvant therapy (chemotherapy, vaccines or experimental agents) within 4 weeks prior to randomization, if the PSA rise and PSADT were documented after the testosterone level was \> 150ng/dL. Patient must have hormone-sensitive prostate cancer as evident by a serum total testosterone level \> 150 ng/dL within 12 weeks prior to randomization. PSA must be \< 30 ng/mL at study entry Patient may not have had therapy modulating testosterone levels (such as luteinizing hormone,releasing-hormone agonists/antagonists and antiandrogens) within 1 year prior to randomization, unless it was in the neoadjuvant and/or adjuvant setting Patient must have evidence of biochemical failure after primary therapy and subsequent progression. Biochemical failure is declared when the PSA reaches a threshold value after primary treatment and it differs for radical prostatectomy or radiation therapy. 1. For radical prostatectomy the threshold for this study is PSA ≥ 0.2ng/mL 2. For radiation therapy the threshold is a PSA rise of 2 ng/mL above the nadir PSA achieved post radiation with or without hormone therapy (2006 RTOG-ASTRO Consensus definition). 3. PSA progression requires a PSA rise above the threshold measured at any time point since the threshold was reached. PSA doubling time between 3 and 9 months. PSA calculation requires two consecutive PSA rises (PSA2 and PSA3) above the threshold PSA (total 3 PSA values); PSA2 and PSA3 must be obtained within 12 months of study entry. All baseline PSAs should be obtained at the same reference lab. Patient's PSA doubling time must be calculated using the following formula (http://www.mskcc.org/nomograms/prostate/psa doubling-time): ECOG performance status less than or equal to 2 Ability to swallow the study drugs Subjects must have normal organ and marrow function as defined below: 1. Absolute neutrophil count greater than or equal to 1,000/mL 2. Hemoglobin greater than or equal to 10 g/dL 3. Platelets greater than or equal to 100,000/mL 4. Total bilirubin within normal institutional limits 5. AST(SGOT)/ALT(SGPT) less than or equal to 1.5 X institutional ULN 6. Creatinine clearance greater than or equal to 60 mL/min/1.73 m2 7. Hgb A1c ≤ 6.5 Exclusion Criteria: Evidence of metastatic disease on imaging studies (CT and/or bone scan) Diagnosis of diabetes mellitus defined as 1. Fasting blood glucose \> 126 mg/dl or, 2. Random blood glucose \> 200 mg/dl 3. Hemoglobin A1C \> 6.5% Need for treatment with any conventional modality for prostate cancer (surgery, radiation therapy, and hormonal therapy) Prior hormonal therapy for recurrent prostate cancer (hormonal therapy given in a neoadjuvant or adjuvant setting and greater than 6 months before entry is acceptable) Treatment within the last 30 days with any investigational drug Radiation therapy within prior 6 months (prophylactic radiotherapy to prevent gynecomastia within 4 weeks prior to randomization is allowed) Known hypersensitivity to metformin Prior history of lactic acidosis Any history of myocardial infarction in the past 12 months Subjects who consume more than 3 alcoholic beverages per day Subjects with serious intercurrent illness, including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or other nonmalignant medical or psychiatric illness that is uncontrolled or whose control may be jeopardized by the complications of this therapy or may limit compliance with the study requirements (at the discretion of the investigator) Patient with previous or concurrent malignancy. Exceptions are made for patients who meet any of the following conditions: Basal cell or squamous cell carcinoma of the skin or prior malignancy that has been adequately treated and patient has been continuously disease free for ≥ 2 years. Subjects currently treated with metformin and/or bicalutamide or who have been treated with metformin and/or bicalutamide in the past 6 months. Subjects who have taken 5a-reductase inhibitors (finasteride or dutasteride), saw palmetto, or PC-SPES within the last 6 weeks are ineligible. Subjects will be eligible for the study after the wash out period of 6 weeks.