In 2007, an estimated 218,890 prostate cancer diagnoses will be made in the United States, accompanied by an estimated 27,050 prostate cancer deaths. Since about 1994 to 1996, with widespread use of serum prostate-specific antigen (PSA) testing and digital rectal examination for prostate cancer screening, and with increased treatment of clinically localized prostate cancer with surgery or radiation therapy, age-adjusted prostate cancer death rates have fallen steadily. Although this trend might indicate a beneficial impact of prostate cancer screening and/or early prostate cancer treatment on prostate cancer mortality, mass screening of the general population for prostate cancer remains controversial. One challenge for prostate cancer screening is the prevalence of the disease in the U.S.: autopsy series have revealed small prostate cancers in as many as 29% of men between age 30 and 40 and 64% of men between age 60 and 70. Obviously, not all of these men are at risk for symptomatic or life-threatening prostate cancer progression. In fact, many such men, if diagnosed with prostate cancer, may be at greater risk for treatment-associated morbidity.