Because the prostate surrounds the urethra, any disease of the gland can cause disturbances in urinary flow, and in the frequency and efficiency with which the bladder is emptied.  There are three common diseases that involve the prostate:

• Benign Prostatic Hyperplasia: BPH is a non-cancerous enlargement of the prostate.  The gradual enlargement of the prostate gland in middle-aged men can cause problems by constricting the urethra, pinching off drainage from the bladder and hence interfering with urination.  BPH is most common in men over 50 and about half of all men will have BPH by the age of 60, rising to eight in ten men (80%) in their eighties.

• Prostate Cancer: This is rare before middle age, with very few cases occurring in men under 50.  Half of all cases occur in men under 75.  Overall the average lifetime risk of a man in England being diagnosed with prostate cancer is about one in eleven (9%).  Most prostate cancers are slow growing and many can be treated effectively or cured, especially if they are caught early.  Prostate cancer is the second most common form of potentially lethal cancer to affect men and is likely to become the most common by 2005.

• Prostatitis: Inflammation or infection of the prostate. This can affect men at any age of their adult life but is not a life-threatening condition.  Prostatitis can be bacterial or non-bacterial.  As the names suggest, bacterial prostatitis is caused by bacteria, whereas with non-bacterial prostatitis, no bacteria are present.  Prostatitis may be acute (i.e. it comes on suddenly and usually only lasts a short time) or chronic (i.e. the symptoms persist or flare up repeatedly over a period of time.)  It is characterized by symptoms of pain and discomfort around the anus, scrotum and the area in between (the perineum).

Each condition is described in detail in later sections, starting with prostate cancer, which is potentially by far the most serious, and then BPH, easily the most common, and concluding with prostatitis which, though less serious than prostate cancer and less common than BPH, can cause distressing and debilitating symptoms among its many sufferers.