The prostate is the gland in men that helps manufacture the fluid in semen (seminal fluid).  It lies between a man's bladder and his rectum and surrounds the urethra (the tube that carries urine from the bladder).  Normally, it's about as big as a walnut.  If it grows too large, it can squeeze the urethra and slow or even stop the flow of urine.

Prostate cancer is one of the conditions that can cause the prostate to grow, and urinary problems are one of its symptoms.  (For more information about the symptoms of prostate cancer, go to Prostate Cancer Key Point # 1).  In America, prostate cancer is the most common form of cancer in men (25% of men diagnosed with cancer have prostate cancer), and the second most common cause of cancer deaths in men.  But unlike many types of cancer, prostate cancer tends to grow slowly.  That's why, when detected early, it's quite curable. 

A variety of conditions can cause symptoms similar to prostate cancer.  The most common of these conditions is BPH (Benign Prostatic Hyperplasia).  

BPH is an enlarged but non-cancerous prostate. The enlargement can lead to urinary problems or changes in urinary habits (such as needing to urinate more often).  Though statistics seem to vary (some studies say 25% of men over 40 and 33% of men over 65 have some BPH symptoms; others say more than 50% of men over 65 have some BPH symptoms), it is clear that BPH is very common in men over 50 and often starts earlier. But for many men with BPH (perhaps 50%) the symptoms are not bothersome enough to need treatment.  

Because this and other conditions have symptoms that mimic prostate cancer, if you do have any symptoms, it's very important to get tested and diagnosed.  Furthermore, in its earliest stages, prostate cancer may not cause any symptoms at all.  That's why an annual prostate cancer screening (being tested for the disease) is recommended for men over 50, whether or not they have any symptoms.  For details about prostate cancer screening go to Prostate Cancer Key Point # 1).