Identification of clinically significant prostate cancer by prostate-specific antigen screening

The importance of screening for early-stage prostate cancer has been debated in the literature. However, there are well-established prognostic factors (Gleason score [GS], pretreatment prostate-specific antigen [PSA], and percent positive biopsy findings [%+Bx]) that predict biologically aggressive disease. These factors, together with a patient's age and general state of health, will permit physicians to project the effect of a prostate tumor over the patient's expected lifetime. This study was performed to determine the proportion of clinically significant prostate cancers diagnosed in a screened population.

From 1991 through 2002, 977 patients with nonpalpable (T1c) prostate cancer were seen for evaluation and comprise the study group. Patients were classified according to pretreatment PSA level, GS, %+Bx, and age.

Based on tumor characteristics alone, 130 patients were noted to be at high risk (GS = 8-10 or PSA level >20 ng/mL; or GS = 7 or PSA level >10-< or =20 ng/mL and >50%+Bx), with a historical 4-year PSA control of 10% to 30% after definitive therapy. An additional 45 patients were at intermediate risk (GS = 7, PSA level >10-< or =20 ng/mL, and 34%-50%+Bx), with a historical 4-year PSA control of 50% to 60% after definitive therapy. Additional patients were identified who had a cumulative anticipated prostate cancer mortality greater than 30% to 50% based on age and GS (GS = 7, age < or =70 years [n = 89]; GS = 6, age < or =65 years [n = 337]). The total at risk for clinically significant tumors was 601 (61.5%) of 977 patients.

A significant proportion of patients with nonpalpable disease diagnosed as having prostate cancer by PSA screening have clinically significant cancers. This supports the continued use of PSA screening.