T-reg Function Changes: a Novel Immune Regulatory Effect Underlying Benefit of Statin Use on Lethal Prostate Cancer

Inclusion Criteria: 1. Men with pathologically-confirmed localized prostate cancer determined to be intermediate (stage T2b, or Gleason 7, or PSA 10-20 ng/mL) or high risk (stage T2c, or PSA \>/=20 ng/mL, or Gleason \>/=8) of biochemical recurrence at the time of biopsy 2. Electing to undergo prostatectomy; 3. Ability to provide written informed consent and willing to complete study procedures. Exclusion Criteria: 1. Current statin use or use of non-statin lipid-lowering drug (fibrates, bile acid sequestrants, or niacin); 2. Current use of medications contraindicated for concomitant use with 40mg simvastatin: * Gemfibrozil * Cyclosporine * Danazol * CYP3A4 inhibitors: itraconazole; ketoconazole; posaconazole; erythromycin; clarithromycin; telithromycin; HIV protease inhibitors; boceprevir; telaprevir; nefazodone 3. Current use of medications requiring lower dose of simvastatin not already listed as exclusions criteria: * Verapamil * Diltiazem * Amiodarone * Ranolazine * Calcium channel blockers: verapamil; diltiazem; amlodipine 4. Men with low-density lipoprotein cholesterol \<50mg/dL 5. Statin use in the previous 12 months; 6. Discontinued statin use because of statin-related adverse event; 7. Evidence or suspicion of metastases; 8. Prior neoadjuvant or adjuvant chemotherapy, hormone therapy, or radiation therapy; 9. History of non-prostate cancer other than non-melanoma skin cancer in the last 24 months; 10. Diagnosed diabetes or currently taking diabetes medications 11. Prior myocardial infarction or stroke 12. Chronic liver disease (hepatitis or cirrhosis) or abnormal liver function (\>1.5x clinical laboratory's upper limit of normal alanine aminotransferase); 13. Stage 4 or 5 chronic kidney disease (Creatinine clearance / estimated glomerular filtration rate \< 30 mL/min calculated by Cockgroft-Gault formula); 14. History of myopathy or inflammatory muscle disease (\>3x clinical laboratory's upper limit of normal creatine kinase).