PROSTATE-CANCER - RELATIVE EFFECTS OF DEMOGRAPHIC, CLINICAL, HISTOLOGIC, AND MR-IMAGING VARIABLES ON THE ACCURACY OF STAGING

PURPOSE: To determine the effects on the accuracy of staging prostate gland cancer of diagnostic prediction rules based on demographic, clin ical, histologic, and magnetic resonance (MR) image variables. MATERIA LS AND METHODS: A total of 200 cases from four medical centers were ev aluated by nine radiologists experienced in MR imaging. The accuracies of the four diagnostic variables (age, prostate specific antigen leve l, Gleason tumor grade, and MR imaging findings) were measured, both s ingly and combined in a particular sequence, by calculating the area i ndex of the receiver operating characteristic curve. RESULTS: The accu racy of staging with single variables (age, 0.58; prostate specific an tigen level, 0.74; Gleason grade 0.73, MR image findings, 0.74) increa sed as the variables were optimally merged. The first two variables co mbined to yield an accuracy of 0.74; the first three combined to yield an accuracy of 0.81; and all four variables resulted in an accuracy o f 0.86. In a clinically important subset of 69 cases for which antigen level and Gleason grade together were inconclusive for the purposes o f staging, the addition of MR imaging findings resulted in an increase in accuracy from 0.55 to 0.73. CONCLUSION: Optimal merging of diagnos tic test results yields an improvement in the accuracy of prostate can cer staging.