What Is Prostate Cancer? Cancer occurs when cells in the body
begin changing and multiplying out of control. These cells can
form lumps of tissue called tumors. Cancer that starts in the
prostate is called prostate cancer. Cancer can grow and spread
beyond the prostate, threatening health and life. Understanding
the Prostate The prostate is a gland about the size and shape of
a walnut. It surrounds the upper part of the urethra in men, the
tube that carries urine from the bladder. The prostate produces
most of the semen in which sperm travel. During orgasm, semen
exits the body through the urethra. When Prostate Cancer Forms
As a man ages, his prostate may change. Inside a changing
prostate, groups of cells may form tumors or other growths. Some
may be benign (not cancerous), but they may still cause
symptoms. Others may be cancerous. Noncancerous growths. As a
man ages, the prostate may grow larger. This condition is called
benign prostatic hyperplasia (BPH). Extra prostate tissue often
squeezes the urethra,