The prostate gland is located at the base of the bladder and it is about the size of a walnut. It secretes a milky fluid that is a component of semen. Since the gland is located directly in front of the rectum, it can be felt by performing a rectal exam. Prostate cancer is the most common cancer other than skin cancer in men in the United States. The American Cancer Society estimates that 230,090 new cases will be diagnosed in 2005. Prostate cancer will cause about 30,350 deaths in 2005 in the United States. Since people are living longer, the incidence of prostate cancer will increase proportionately. Prostate cancer is now being diagnosed more frequently partly secondary to the widespread utilization of the Prostate Specific Antigen (PSA) blood test.
Having a family history of prostate cancer is the most significant risk factor. The incidence of prostate cancer is also increased in African-Americans. Environmental factors may contribute to the development of prostate cancer. There is an increased incidence in persons migrating to the United States from areas with a low incidence of prostate cancer. Certain industries are associated with an excess of prostate cancer. These include workers that are exposed to cadmium, workers in tire and rubber manufacturing, farmers, mechanics, and sheet metal workers.
PRESENTATION AND DIAGNOSIS
SCREENING FOR PROSTATE CANCER
The American Cancer Society recommends a yearly digital rectal exam starting at age 50. They also recommend a yearly prostate specific antigen (PSA) blood test beginning at age 50. The PSA test measures a protein in the blood that increases with the development of prostate cancer. Unfortunately this test is far from perfect. There are many false positive as well as false negative results. There is quite a bit of disagreement on this recommendation. We do not know whether early detection will reduce mortality. At least 30% of men over 50 years of age have definite evidence of prostate cancer, yet only a small fraction of these cancers will progress to cause death. There is presently no perfect way to predict which cancers will progress and spread. An article in The New England Journal of Medicine concluded that watchful waiting is a reasonable option for men with localized early prostate cancer, especially if their life expectancy is less than 10 years. Men that are in their fifties or sixties, are likely to improve their life expectancy with treatment. Microscopic evaluation of the biopsy specimens can be helpful in classifying the cancer as to its potential for spread. If the PSA is over 4 ng/ml or if the rectal exam is abnormal, a biopsy is usually preformed using transrectal ultrasonography. This test can show abnormal areas in the prostate that are most likely to have cancer. If the yearly PSA tests increase by more than 0.75 ng/ml, a biopsy should also be performed. It is a good idea to repeat any elevated PSA since there is a daily variation is the values.
There are presently several different options for treatment. Radical prostatectomy involves removal to the entire prostate gland. Younger patients are more likely to undergo a prostatectomy. The overall 15-year survival rate is between 80% and 85% when the initial cancer is confined to the prostate gland. A prostatectomy leaves at least 30% of patients impotent and 1%-2 % incontinent. Radiation involves external beam radiation to the prostate gland or brachytherapy where radium implants are inserted into the prostate gland. Radiation therapy has an impotence rate of about 25% and an incontinence rate of almost zero. Unfortunately, some cancer is left behind about 10% of the time in both methods. Hormonal therapy is usually reserved for patients who have advanced prostate cancer.
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