Impact of positive surgical margin status in predicting early biochemical recurrence after robot-assisted radical prostatectomy

Background We investigated the association between positive surgical margin (PSM) status and biochemical recurrence (BCR) after robot-assisted radical prostatectomy (RARP) to develop a prognostic factor-based risk stratification model for BCR. Methods We analyzed the data of 483 patients who underwent RARP at our hospital between October 2010 and April 2019; 435 patients without neoadjuvant therapy were finally included. The BCR-free survival rate was determined using Kaplan-Meier analysis. Effects of the PSM status, including the number of PSMs, Gleason score (GS) at a PSM, and the maximum PSM length for BCR, were investigated using Cox regression analysis. Results BCR was confirmed after RARP in 61 patients (14.0%), and PSM was confirmed in 74 patients (17.0%); PSM was a significant predictor of BCR (p < 0.001). The median number of PSMs was 2 (1-6), and the median maximum length of PSM was 6.0 (2.0-17.0) mm. Multivariable analysis showed lymph node invasion (p < 0.001), GS of >= 7 at a PSM (p = 0.022) and a maximum PSM length of > 6.0 mm (p = 0.003) were significant predictors of BCR. We classified the patients without lymph node invasion into good-, intermediate-, and poor-risk groups according to the other two risk factors (presence of 0, 1, and 2 factors, respectively) and rates of 1-year BCR-free survival (100.0, 72.7, and 48.1%, respectively). Conclusion Higher GS at PSM and greater length of PSM were significant predictors of BCR after RARP, and console surgeons should be careful to prevent PSM during RARP.