Because it is often caused by something blocking elimination of urine made by the kidneys.

This nagging problem could be reversed, unless the obstruction is long enough to cause damage to kidney tissue present. Obstruction of 1 or both ureters can be caused by the next: Kidney stone, usually just on one side Cancers of the urinary tract organs, kidney tumor or cancer, or structures near the urinary system that may obstruct the outflow of urine Medications Obstruction at the bladder level can be caused by the next: Bladder stone Enlarged prostate Blood clot Bladder cancer Neurologic disorders of the bladder impairing its ability to contract Treatment consists of relieving the obstruction.Rittmaster, M.D.1 The benefits of the Prostate Cancer tumor Prevention Trial showed that finasteride, in comparison with placebo, reduced the risk of prostate cancer by 25 percent, but among the tumors that were detected, there was a 27 percent increase in the amount of those that experienced Gleason scores of 7 to 10.2 A subsequent analysis showed that the chances ratio for tumors with Gleason ratings of 7 to 10 in the finasteride group reduced from 1.27 to 1 1.03 in a logistic model that included both baseline variables which are known to have an effect on the risk of cancers and the post-baseline prostate volume. Expression of type 1 in the prostate is enhanced through the advancement of prostate cancer, whereas the expression of type 2 is reduced or unchanged.