Prostate Cancer Overview
Prostate cancer is the most common type of cancer in men in the United States (other than skin cancer). Of all the men who are diagnosed with cancer each year, more than one-fourth have prostate cancer.
Research is increasing our understanding of prostate cancer. Scientists are learning more about the possible causes of prostate cancer and are looking for new ways to prevent, detect, diagnose, and treat this disease. Because of this research, men with prostate cancer now have a lower chance of dying from the disease.
The Prostate
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 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.
Understanding the Cancer Process
Cancer is a group of many related diseases. These diseases begin in cells, the body's basic unit of life. Cells have many important functions throughout the body.
Normally, cells grow and divide to form new cells in an orderly way. They perform their functions for a while, and then they die. This process helps keep the body healthy.
Sometimes, however, cells do not die. Instead, they keep dividing and creating new cells that the body does not need. They form a mass of tissue, called a growth or tumor.
Tumors can be benign or malignant:
- Benign tumors are not cancer. They can usually be removed, and in most cases, they do not come back. Cells from benign tumors do not spread to other parts of the body. Most important, benign tumors of the prostate are not a threat to life.
Benign prostatic hyperplasia (BPH) is the abnormal growth of benign prostate cells. In BPH, the prostate grows larger and presses against the urethra and bladder, interfering with the normal flow of urine. More than half of the men in the United States between the ages of 60 and 70 and as many as 90 percent between the ages of 70 and 90 have symptoms of BPH. For some men, the symptoms may be severe enough to require treatment. - Malignant tumors are cancer. Cells in these tumors are abnormal. They divide without control or order, and they do not die. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream and lymphatic system. This is how cancer spreads from the original (primary) cancer site to form new (secondary) tumors in other organs. The spread of cancer is called metastasis.
When prostate cancer spreads (metastasizes) outside the prostate, cancer cells are often found in nearby lymph nodes. If the cancer has reached these nodes, it means that cancer cells may have spread to other parts of the body -- other lymph nodes and other organs, such as the bones, bladder, or rectum. When cancer spreads from its original location to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if prostate cancer spreads to the bones, the cancer cells in the new tumor are prostate cancer cells. The disease is metastatic prostate cancer; it is not bone cancer.
National Cancer Institute (NCI) booklet (NIH Publication No. 05-1576)
Posted July 2006
