Prostate

Prostate cancer is the most common cancer in North American males and the second leading cause of death among men who die from cancer (Carter and Partin; Narayan; Pienta; Weiss and Fair). Despite its high incidence of diagnosis, there is an even greater incidence of prostate cancers that go unrecognized. The biological behavior of the clinically recognized cancers is highly variable. For those with less aggressive tumors, prognosis is excellent with or without treatment, whereas for those with more aggressive tumors prognosis is poor regardless of treatment. For these reasons the most appropriate treatment for various stages of cancer creates confusion and controversy as physicians attempt to predict the behavior of individual tumors.

Like BPH, prostate cancer is strongly associated with aging. It is rarely diagnosed in men under forty, but, starting at that age, its incidence increases progressively, reaching a peak in the eighth decade. Autopsy studies have shown microscopic evidence of prostate cancer in 30 percent of 50-year-old males and up to 50 percent of men over seventy-five. However, it is estimated that only about 20 percent of cancers found at autopsy are clinically significant (Carter and Partin; Pienta; Walsh; Weiss and Fair). Prostate cancer, like BPH, is affected by male hormones. It does not develop in castrated men and grows in the presence of male hormones; removal of male hormones by castration induces dramatic regression of cancer growth.

Most prostate cancer is diagnosed by means of either an elevated prostate-specific antigen (PSA) or abnormal digital rectal exam of the prostate. Management decisions are based on whether the tumor is confined to the prostate; the grade (microscopic appearance) of the tumor; the presence of metastatic disease; and the general medical condition and life expectancy of the patient. For healthy patients with no medical contraindications and a life expectancy longer than ten years who have localized prostate cancer, most urologists would advocate surgical removal of the prostate and lymph nodes. External beam radiation therapy is also used as a primary treatment of localized prostate cancer. Implantation of radioactive sources into the prostate has gained renewed interest since the 1990s for the treatment of prostate cancer. For prostate cancer that has invaded through the prostate capsule (metastasized), surgery or local noninvasive treatments are not effective. Treatment at this point is aimed at removing the active stimulation of cancer cell growth by removal of hormone sources. Given that 95 percent of the body's testosterone is produced by the testes, the simplest way of accomplishing this is by removal of the testes, or bilateral orchidectomy. The same effect can be achieved pharmacologically by using analogues of luteinizing hormone-releasing hormone, which block the pathway leading to the production of testosterone by the testes in combination with anti-androgens that block the effects of the androgens at the target tissues.