Prostate cancer is a group of cancerous cells (a malignant tumor) that begins most often in the outer part of the prostate. It is the second most common type of cancer in men in the United States. Skin cancer is the most common. Of all the men who are diagnosed with cancer each year, more than one-fourth have prostate cancer.
The prostate is a gland in a man's reproductive system. It makes and stores seminal fluid, a milky fluid that nourishes sperm. This fluid is released to form part of semen.
The prostate is about the size of a walnut. It is located below the urinary bladder and in front of the rectum. It surrounds the upper part of the urethra, the tube that empties urine from the bladder. If the prostate grows too large, the flow of urine can be slowed or stopped.
To work properly, the prostate needs male hormones (androgens). Male hormones are responsible for male sex characteristics. The main male hormone is testosterone, which is made mainly by the testicles. Some male hormones are produced in small amounts by the adrenal glands.
The causes of prostate cancer are not well understood. Doctors cannot explain
why one man gets prostate cancer and another does not.
Researchers are studying factors that may increase the risk of this disease. Studies have found that the following risk factors are associated with prostate cancer:
- Age. In the United States, prostate cancer is found mainly in men over age 55. The average age of patients at the time of diagnosis is 70.
- Family history of prostate cancer. A man's risk for developing prostate cancer is higher if his father or brother has had the disease.
- Race. This disease is much more common in African American men than in white men. It is less common in Asian and American Indian men.
- Diet and dietary factors. Some evidence suggests that a diet high in animal fat may increase the risk of prostate cancer and a diet high in fruits and vegetables may decrease the risk. Studies are in progress to learn whether men can reduce their risk of prostate cancer by taking certain dietary supplements.
Although a few studies suggested that having a vasectomy might increase a man's risk for prostate cancer, most studies do not support this finding. Scientists have studied whether benign prostatic hyperplasia, obesity, lack of exercise, smoking, radiation exposure, or a sexually transmitted virus might increase the risk for prostate cancer. At this time, there is little evidence that these factors contribute to an increased risk.
Common Cancer Types
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