Prostate cancer is cancer of the prostate gland. It is the third-leading cause of cancer death for men in the United States. About 1 in 7 men will be diagnosed with it in their lifetime. About 1 in 39 men will die from it. Growths in the prostate can be benign (not cancer) or malignant (cancer).
Benign growths (such as benign prostatic hypertrophy):
- Are rarely a threat to life
- Don't invade the tissues around them
- Don't spread to other parts of the body
- Can be removed and can grow back very slowly (however, it doesn't usually grow back)
Malignant growths (prostate cancer):
- May sometimes be a threat to life
- Can invade nearby organs and tissues (such as the bladder or rectum)
- Can spread to other parts of the body
- Often can be removed but sometimes grow back
Prostate cancer cells can spread by breaking away from a prostate tumor. They can travel through blood vessels or lymph vessels to reach other parts of the body. After spreading, cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues. When prostate cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary (original) tumor. For example, if prostate cancer spreads to the bones, the cancer cells in the bones are actually prostate cancer cells. The disease is metastatic prostate cancer, not bone cancer. For that reason, it's treated as prostate cancer, not bone cancer.
To understand prostate cancer, it helps to know how the prostate normally works.
Male reproductive system
The prostate is part of the male reproductive system. It is about the size of a walnut and weighs about an ounce. The prostate is below the bladder and in front of the rectum. The prostate goes all the way around a tube called the urethra. The urethra carries urine from the bladder out through the penis. The main job of the prostate is to make fluid for semen. During ejaculation, sperm made in the testicles moves to the urethra. At the same time, fluid from the prostate and the seminal vesicles also moves into the urethra. This mixture—semen—goes through the urethra and out of the penis.