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Facts About Prostate Cancer

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What Is Prostate Cancer?

Most cancers are named after the part of the body where the cancer first starts. Prostate cancer starts in the prostate gland. The prostate gland is found only in men; therefore, only men get prostate cancer. The prostate is about the size of a walnut. It is just below the bladder and in front of the rectum. The tube that carries urine (urethra) runs through the prostate.

The prostate gland makes a fluid that is part of semen, the fluid that contains sperm. Nerves found next to the prostate take part in causing an erection of the penis, and treatments that remove or damage these nerves can cause problems with erections called impotence.

Most of the time, prostate cancer grows very slowly. Autopsy studies show that many elderly men who died of other diseases also had prostate cancer that neither they nor their doctor were aware of.

But sometimes it can grow quickly, spreading to other parts of the body. Cancer cells may enter the lymph system and spread to lymph nodes (small, bean-shaped collections of cells that help in fighting infections).

If cancer is in the lymph nodes, it is more likely to have spread to other organs of the body as well.

How Many Men Get Prostate Cancer?

Prostate cancer is the most common type of cancer found in American men, other than skin cancer. The American Cancer Society estimates that there will be about 198,100 new cases of prostate cancer in the United States in 2001. About 31,500 men will die of this disease. Although men of any age can get prostate cancer, it is found most often in men over 50. In fact, more than 8 out of ten of the men with prostate cancer are over the age of 65.

Prostate cancer is about twice as common among African-American men as it is among white American men. It is also most common in North America and northwestern Europe. It is less common in Asia, Africa, Central America, and South America.

What Causes Prostate Cancer? Can It Be Prevented?

We don't yet know exactly what causes prostate cancer. There may be a link to a certain gene that causes some men to get prostate cancer. Genes are the basic units of heredity. Having certain genes in the family can result in a higher risk of getting prostate cancer, but these genetic changes appear to be linked to only about 10% of prostate cancers.

We do know that certain risk factors are linked to prostate cancer. A risk factor is something that increases a person's chance of getting a disease. Some risk factors, such as diet, can be controlled. Others, like a person's age or race, can't be changed. While all men are at risk for prostate cancer, the factors listed below can increase the chances of having the disease.

  • Age: the chance of getting prostate cancer goes up with age.

  • Race: for unknown reasons, prostate cancer is more common among African-American men than among white men.

  • Diet: a diet high in fat may play a part in causing prostate cancer.

  • Family: men with close family members who have had prostate cancer are more likely to get prostate cancer themselves.

Because the exact cause of prostate cancer is not known, we can't say if it is possible to prevent most cases of the disease. Since a high-fat diet may be linked to prostate cancer, the American Cancer Society suggests a diet low in animal fat and high in vegetables, fruits, and grains.

These guidelines provide an overall healthful approach to eating that also helps lower the risk for some other types of cancer. Tomatoes, grapefruit, and watermelon are rich in a substance (lycopenes) that helps prevent damage to DNA and may help lower prostate cancer risk.

How Is Prostate Cancer Found?

There are still many uncertainties about finding prostate cancer early. Cancers found early by using the PSA blood test or the digital rectal exam (see below) are often smaller and have spread less than cancers found because of the symptoms they cause. But prostate cancer is unlike many other cancers in that it often grows very slowly. If the cancer has not spread beyond the prostate, the five-year relative survival rate is nearly 100%, whether or not the cancer is treated. Therefore, it is not clear as to whether treatment will help all men with prostate cancer live longer.

On the other hand, before these tests were widely used, most men with prostate cancer were found to have advanced disease, and most died within a few years after the cancer was found.

Although finding and treating prostate cancer early may help some men to live longer, it will have no impact on the life span of other men. And prostate cancer treatments can affect a man's quality of life because of side effects such as impotence and incontinence.

The PSA blood test measures a protein (prostate specific antigen) made by prostate cells. PSA blood test results are reported as ng/ml which stands for nanograms per milliliter. Results under 4 ng/ml are usually considered normal. Results over 10 ng/ml are high, and values between 4 and 10 are considered borderline. The higher the PSA level, the more likely the chance of prostate cancer. While PSA levels tell how likely a man is to have prostate cancer, the results do not provide a definite diagnosis. Men with a high PSA result are advised to have a biopsy to find out whether or not they have cancer.

To do the digital rectal exam (DRE), the doctor inserts a gloved finger into the rectum to feel for lumps on the prostate. The prostate gland is found next to the rectum, and most cancers begin in the part of the gland that can be reached by a rectal exam. While it is uncomfortable, the exam causes no pain and takes only a short time. Until more is known, the decision about whether or not a man should be tested for prostate cancer should be left up to the man and his doctor after they discuss the pros and cons of testing.

The American Cancer Society believes that doctors should offer the PSA blood test and digital rectal exam to men who have at least a 10-year life expectancy beginning at age 50, and to younger men, beginning at 45 years, who are at high risk. Doctors should talk to their patients about the possible risks and benefits of finding and treating the cancer early. Dr. Mansfield from the University of Maryland School of Medicine recommends that the PSA test be performed at age 40 for men at high risk.

*Information gathered from the American Cancer Society.