Digital rectal examination for detecting prostate cancer at prostate specific antigen levels of 4 ng/ml or less

Purpose: We evaluated the detection rate of prostate cancer in men with sus picious digital rectal examination findings and serum prostate specific ant igen (PSA) 4 ng./ml. or less. We also evaluated the stage and grade of canc ers detected. Materials and Methods: We screened 22,513 community volunteers by PSA testi ng and digital rectal examination at 6-month intervals. Biopsy was recommen ded when either test was suspicious for cancer. In the subset of 2,703 whit e and black men in whom PSA was 4 ng./ml. or less and digital rectal examin ation was suspicious for prostate cancer we compared compliance with biopsy recommendations, cancer detection rates, and stage and grade of cancers de tected. We then correlated these results with patient age, race and serum P SA concentration. We performed multivariate logistic regression analysis to predict cancer based on clinical characteristics, and evaluated the positi ve predictive value of digital rectal examination for detecting cancer as s tratified by race and PSA. Results: Of the men 70% underwent biopsy with no difference in compliance a ccording to age, race or PSA level. The 13% cancer detection rate correlate d with age, race and PSA (p <0.003). The positive predictive value of a sus picious digital rectal examination was 5, 14 and 30% in men with PSA 0 to 1 .0, 1.1 to 2.5 and 2.6 to 4.0 ng./ml., respectively. All cancers were clini cally localized. Of the 72% of cases that were surgically staged 82% were o rgan confined and 78% were moderately differentiated. Conclusions: The positive predictive value of suspicious digital rectal exa mination was appreciable in men with low serum PSA. The majority of cancer cases detected by digital rectal examination had features of clinically imp ortant and potentially curable disease.