The prostate is a male sex gland that is about the size of a walnut. It produces a thick fluid that is a normal component of semen in men. Prostate cancer develops from normal prostate cancer cells that become abnormal over time and begin dividing more than normal. Prostate cancer is the most common cancer among men in the United States after non-melanoma skin cancer, and is the third leading cause of cancer-related deaths. Prostate cancer is expected to be diagnosed in 241,740 men in 2012 . Because of widespread screening efforts, the majority of newly diagnosed prostate cancers are found early when they are still confined to the prostate gland, thus the number of prostate cancer-related deaths has decreased. Most prostate cancer diagnosed in the United States is organ-confined prostate cancer, that is the cancer is limited just to the prostate gland.