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, clinical, histologic, and magnetic resonance (MR) image variables. MATERIALS AND METHODS: A total of 200 cases from four medical centers were evaluated by nine radiologists experienced in MR imaging. The accuracies of the four diagnostic variables (age, prostate specific antigen level, Gleason tumor grade, and MR imaging findings) were measured, both singly and combined in a particular sequence, by calculating the area index of the receiver operating characteristic curve. RESULTS: The accuracy of staging with single variables (age, 0.58; prostate specific antigen level, 0.74; Gleason grade 0.73, MR image findings, 0.74) increased as the variables were optimally merged. The first two variables combined 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 of 0.86. In a clinically important subset of 69 cases for which antigen level and Gleason grade together were inconclusive for the purposes of staging, the addition of MR imaging findings resulted in an increase in accuracy from 0.55 to 0.73. CONCLUSION: Optimal merging of diagnostic test results yields an improvement in the accuracy of prostate cancer staging.