Men once they cross 50 years of age are advised to go for a PSA test annually to keep a tab on their prostate health. PSA (prostate-specific antigen) test is usually done to assess the health of the prostate gland. With age the prostate gland enlarges and leads to various problems. While enlarged prostate is not an alarming condition but a sign of ageing it is better to keep a tab on how the gland is progressing to check if there is a risk of developing prostate cancer in future. Here are reasons why prostate is considered a silent killer.