Abstract
BACKGROUND: The risk of biochemical recurrence (BCR) following radical prostatectomy for pathologic Gleason 7 prostate cancer varies according to the proportion of Gleason 4 component. OBJECTIVE: We sought to explore the value of several novel quantitative metrics of Gleason 4 disease for the prediction of BCR in men with Gleason 7 disease. DESIGN, SETTING, AND PARTICIPANTS: We analyzed a cohort of 2630 radical prostatectomy cases from 1990-2007. All pathologic Gleason 7 cases were identified and assessed for quantity of Gleason pattern 4. Three methods were used to quantify the extent of Gleason 4: a quantitative Gleason score (qGS) based on the proportion of tumor composed of Gleason pattern 4, a size-weighted score (swGS) incorporating the overall quantity of Gleason 4, and a size index (siGS) incorporating the quantity of Gleason 4 based on the index lesion. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Associations between the above metrics and BCR were evaluated using Cox proportional hazards regression analysis. RESULTS AND LIMITATIONS: qGS, swGS, and siGS were significantly associated with BCR on multivariate analysis when adjusted for traditional Gleason score, age, prostate specific antigen, surgical margin, and stage. Using Harrell's c-index to compare the scoring systems, qGS (0.83), swGS (0.84), and siGS (0.84) all performed better than the traditional Gleason score (0.82). CONCLUSIONS: Quantitative measures of Gleason pattern 4 predict BCR better than the traditional Gleason score. PATIENT SUMMARY: In men with Gleason 7 prostate cancer, quantitative analysis of the proportion of Gleason pattern 4 (quantitative Gleason score), as well as size-weighted measurement of Gleason 4 (size-weighted Gleason score), and a size-weighted measurement of Gleason 4 based on the largest tumor nodule significantly improve the predicted risk of biochemical recurrence compared with the traditional Gleason score.