Importance of Reporting the Gleason Score at the Positive Surgical Margin Site: Analysis of 4,082 Consecutive Radical Prostatectomy Cases

Abstract

Since 2010 pathologists at our institution have routinely been documenting the Gleason score at the margin and length of the positive surgical margin after prostatectomy. In this study we evaluate how the Gleason score and positive surgical margin length correlate with the grade and adverse pathological characteristics of the final specimen, and whether the positive surgical margin Gleason score affects the risk of early biochemical recurrence. A total of 4,082 consecutive patients undergoing radical prostatectomy and pelvic lymph node dissection between 2010 and 2014 for localized prostate cancer were included in the study, of whom 405 had a Gleason score of 7 or greater of the primary nodule and a positive surgical margin with the length and Gleason score recorded at the margin. Concordance rates between the Gleason score at the margin and the final pathological specimen were compared. Logistic regression models were used to predict the risk of unfavorable pathology. Cox proportional hazards models controlling for Gleason score, preoperative prostate specific antigen, pathological stage and adjuvant radiation were used to predict biochemical recurrence, and Kaplan-Meier estimates of recurrence-free survival were calculated by Gleason score. Among patients with positive margins biochemical recurrence was identified in 22% (vs 5.6% without positive margins), metastases in 3% (vs 0.5%) and adjuvant radiation in 30% (vs 4.1%). Mean followup was 22 months (range 12 to 48). The Gleason score at the positive surgical margin was the same as the final pathology specimen in 44% of patients, and a lower Gleason score in 56% of patients. A shorter positive surgical margin was independently associated with a lower Gleason score at the margin (p=0.02). Kaplan-Meier estimates demonstrated improved freedom from biochemical recurrence among patients with a lower Gleason score at the margin. In multivariate Cox models having a lower grade margin was associated with a decreased risk of biochemical recurrence (HR 0.50, OR 0.25-0.97). A lower Gleason score at the positive surgical margin is independently associated with a shorter margin length and a decreased risk of early biochemical recurrence. Thus, the Gleason score at the margin should be documented.