This study is for individuals electing to have GreenLight Photoselective Vaporization of the Prostate (PVP) to treat symptoms from an enlarged prostate gland. The purpose of this research study is to evaluate the safety and effectiveness of the medication dutasteride as compared to placebo (an inactive substance) for improving surgical and long-term outcomes of PVP. Dutasteride is approved by the United States Food and Drug Administration (FDA) for the treatment of symptoms from an enlarged prostate gland. The use of dutasteride to improve the outcomes of PVP is investigational. The study will last for approximately 15 months and will involve 6 visits.