Correlation between prostate specimen density and positive surgical margins in patients after radical prostatectomy for prostate cancer

Objective To investigate the correlation between postoperative prostate specimen density and positive surgical margins in patients undergoing radical prostatectomy for prostate cancer, and to provide reference for clinical assessment of postoperative recurrence risk and optimization of subsequent treatment strategies. Methods A total of 153 patients who underwent robot-assisted radical prostatectomy for prostate cancer at Northern Jiangsu People's Hospital from November 2023 to August 2025 were retrospectively selected. Clinical baseline data were collected, including age, postoperative prostate specimen weight and volume, postoperative Gleason score, operation duration, intraoperative blood loss, prostate-specific antigen (PSA), clinical T stage, and extracapsular extension. Postoperative specimen weight (with seminal vesicles removed) was measured using an electronic balance (precision: 0.01 g). Specimen volume was determined using the water displacement method (the specimen was fully submerged in a graduated cylinder filled with normal saline, and the increase in liquid volume was recorded). Specimen density was calculated as weight/volume (g/cm3). Positive surgical margin status was determined based on pathological examination of the surgical specimen (defined as cancer cells observed at the inked resection margin under microscopy). Spearman correlation analysis was used to assess the relationship between prostate specimen density and positive surgical margins. Multivariate logistic regression was performed to identify independent risk factors for positive surgical margins. Results Among the 153 patients, 37 (24.2%) had positive surgical margins and 116 (75.8%) had negative margins. A statistically significant difference in prostate specimen density was observed between the positive and negative margin groups (t=-6.96, P<0.001). Spearman correlation analysis showed that prostate specimen density was positively correlated with positive surgical margin rate (r=0.462, P<0.001). Multivariate logistic regression analysis indicated that Gleason score and specimen density were independent risk factors for positive surgical margins after radical prostatectomy. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) for prostate specimen density (AUC=0.812) was slightly higher than that of the Gleason score (AUC=0.801). The optimal cutoff values were 1.111 g/cm3 and 2.50, respectively (corresponding to ISUP grade≥3). Conclusions Prostate specimen density after radical prostatectomy is significantly positively correlated with positive surgical margins and serves as an independent risk factor. In clinical practice, postoperative prostate specimen density combined with Gleason score and other indicators may help predict the risk of positive surgical margins in patients after radical prostatectomy.