To the Editor.
—Dr Catalona and colleagues,1 reporting on a prospective study using PSA in detecting prostate cancer, concluded that "[f]ree serum PSA measurements may reduce the number of additional biopsies required by the lower PSA cutoff" in men with PSAs in the range of 2.6 to 4.0 ng/mL. One of us2 previously analyzed data from a study of Gann et al3 showing that their PSA stratum of 2.1 to 4.0 ng/mL provided no information to increase or decrease the probability of aggressive prostate cancer because the 95% confidence intervals of the likelihood ratio for this stratum included 1.0. Unfortunately, the study by Catalona et al did not report the usual operating characteristics for screening and diagnostic tests, ie, sensitivity, specificity, likelihood ratios, and the area under the receiver operating characteristic curve for using the percentage of free PSA.Of the 332 men described, 317 had free PSA measurements, and 72 of these men (23%) had cancer and
Peirce JC, Hoffman RM, Clanon DL. PSA Thresholds for Prostate Cancer Detection. JAMA. 1997;278(9):700. doi:10.1001/jama.1997.03550090024015