Prostate cancer detection in men with serum PSA concentrations of 2.6 to 4.0 ng/mL and benign prostate examination. Enhancement of specificity with free PSA measurements

Abstract

Objective: To determine the detection rate of prostate cancer in a screening population of men with prostate-specific antigen (PSA) concentrations of 2.6 to 4.0 ng/mL and a benign prostate examination, to assess the clinicopathological features of the cancers detected, and to assess the usefulness of measuring the ratio of free to total PSA to reduce the number of prostatic biopsies.

Design: A community-based study of serial screening for prostate cancer with serum PSA measurements and prostate examinations.

Setting: University medical center.

Subjects: A total of 914 consecutive screening volunteers aged 50 years or older with serum PSA levels of 2.6 to 4.0 ng/mL who had a benign prostate examination and no prior screening tests suspicious for prostate cancer, 332 (36%) of whom underwent biopsy of the prostate.

Main outcome measures: Cancer detection rate, clinical and pathological features of cancers detected, and specificity for cancer detection using measurements of percentage of free PSA.

Results: Cancer was detected in 22% (73/332) of men who underwent biopsy. All cancers detected were clinically localized, and 81% (42/52) that were surgically staged were pathologically organ confined. Ten percent of the cancers were clinically low-volume and low-grade tumors, and 17% of those surgically staged were low-volume and low-grade or moderately low-grade tumors (possibly harmless). Using a percentage of free PSA cutoff of 27% or less as a criterion for performing prostatic biopsy would have detected 90% of cancers, avoided 18% of benign biopsies, and yielded a positive predictive value of 24% in men who underwent biopsy.

Conclusions: There is an appreciable rate of detectable prostate cancer in men with serum PSA levels of 2.6 to 4.0 ng/mL. The great majority of cancers detected have the features of medically important tumors. Free serum PSA measurements may reduce the number of additional biopsies required by the lower PSA cutoff.