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The prostate is a walnut-sized gland that forms part of the male reproductive system. The gland is made of two lobes, or regions, enclosed by an outer layer of tissue. As the diagrams show, the prostate is located in front of the rectum and just below the bladder, where urine is stored. The prostate also surrounds the urethra, the canal through which urine passes out of the body.
Scientists do not know all the prostate's functions. One of its main roles, though, is to squeeze fluid into the urethra as sperm move through during sexual climax. This fluid, which helps make up semen, energizes the sperm and makes the vaginal canal less acidic.
One of the gland's main roles is to squeeze fluid into the urethra as sperm move through during sexual climax.
What is Prostate Cancer?
Prostate cancer develops from cells of the prostate gland. Eventually the cancer cells may spread outside the gland to other parts of the body. Most prostate cancers grow very slowly. Autopsy studies show that many elderly men who died of other diseases also had a prostate cancer that neither they nor their doctor were aware of. But some prostate cancers can grow and spread quickly.
The prostate gland is about the size of a walnut and is located in front of the rectum, behind the base of the penis, and under the bladder. It is found only in men, and contains gland cells that produce some of the seminal fluid, which protects and nourishes sperm cells.
The prostate surrounds the upper part of the urethra, the tube that carries urine and semen out of the penis. Nerves located next to the prostate take part in causing an erection of the penis, and treatments that remove or damage these nerves can cause erectile dysfunction, also known as impotence.
Lymph is a clear fluid that contains tissue waste products and immune system cells. Lymphatic vessels carry this fluid to lymph nodes (small, bean-shaped collections of immune system cells important in fighting infections). Most lymphatic vessels of the prostate lead to pelvic lymph nodes. Cancer cells can enter lymph vessels and spread out along these vessels to reach lymph nodes, where they can continue to grow. If prostate cancer cells have multiplied in the pelvic lymph nodes, they are more likely to have spread to other organs of the body as well.
Although several other cell types are found in the prostate, over 99% of prostate cancers develop from glandular cells. The medical term for a cancer that starts in glandular cells is adenocarcinoma. Because other types of prostate cancer are so rare, when someone speaks of prostate cancer it is assumed they are referring to a prostatic adenocarcinoma, unless they specifically mention some other cell type.
Prostatic intraepithelial neoplasia (PIN) is a condition in which there are changes in the microscopic appearance (the size, shape, or the rate at which they multiply) of prostate epithelial cells. Older men are more likely to have this condition. PIN is classified as either low grade or high grade. If a person has high grade PIN, repeat biopsies and PSA tests should be done regularly. PIN may lead to the development of prostate cancer. At this time there is no standard treatment for PIN. Studies are being done to determine if treatments used for BPH (benign prostatic hyperplasia) are also effective in treating PIN.
WHAT ARE THE KEY STATISTICS ABOUT PROSTATE CANCER?
Prostate cancer is the most common cancer, excluding nonmelanoma skin cancers, in American men. The American Cancer Society estimates during 2000 approximately 180,400 new cases of prostate cancer will be diagnosed in the United States.
Prostate cancer is the second leading cause of cancer death in men, exceeded only by lung cancer. The American Cancer Society estimates that 31,900 men in the United States will die of this disease during 2000. Prostate cancer accounts for about 11% of male cancer-related deaths.
The 5-year survival rates discussed in this section refer to the percent of men who live at least 5 years after their cancer is diagnosed. It is important to remember that many of these men live much longer than 5 years after diagnosis. Of course, 5-year survival rates are based on patients diagnosed and initially treated more than 5 years ago. Improvements in treatment often result in a more favorable outlook for recently diagnosed men. And the survival statistics in this section include all men diagnosed with prostate cancer, regardless of their treatment. The prognosis for a man depends on the extent of his cancer but is also affected by factors such as the treatment he chooses and other individual aspects of his medical situation.
Eighty-nine percent of men diagnosed with prostate cancer survive at least 5 years, and 63% survive at least 10 years. Fifty-eight percent of all prostate cancers are found while they are still localized (that is, confined to the prostate), and the 5-year relative survival rate for men with localized prostate cancer is 100%. Thirty-one percent of prostate cancers have already spread locally (to tissues near the prostate) at the time of diagnosis. The 5-year survival rate for these men is 94%. Among the 11% of men whose prostate cancers have already spread to distant parts of the body at the time of diagnosis, about 31% are expected to survive at least five years.
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