Intraoperative frozen section of the prostate decreases positive margin rate while ensuring nerve sparing procedure during radical prostatectomy

Abstract

Purpose: We evaluated whether intraoperative frozen section analysis of the prostate surface might provide significant information to ensure nerve sparing and minimize the positive margin rate.

Materials and methods: In 236 patients treated with radical prostatectomy between June 2011 and September 2012 whole surface frozen section analysis of the removed prostate was done intraoperatively. The apex and base were circumferentially dissected as well as the whole posterolateral tissue corresponding to the neurovascular bundles. Multiple perpendicular sections were cut systematically for frozen section analysis. Pathology results were reported to navigate the procedure.

Results: Frozen section analysis identified positive surgical margins in 22% of cases, including the neurovascular bundles in 56.9%, apex in 34.5% and base in 8.6%. Of positive frozen section cases 92.3% could be converted to negative status, while 7.7% remained positive. The final positive margin rate in the total cohort was 3%, including a false-negative frozen section rate of 1.6%. In 14.8% of cases the initial nerve sparing plan was changed intraoperatively due to the positive frozen section and the secondary resected specimen detected cancer in 25%. Final pathology results showed Gleason upgrading or up-staging in 40.7% of cases compared to preoperative variables. When comparing patients with positive vs negative frozen sections, preoperative variables did not significantly differ, while postoperatively pathological stage, tumor volume, operative time and final margin status differed significantly. Of patients with exclusively unilateral positive biopsies 13% had a positive surgical margin intraoperatively on the opposite, biopsy negative side.

Conclusions: The surface frozen section technique is associated with a low false-negative surgical margin rate. It might allow for safer preservation of functional anatomical structures in misclassified patients or even patients at higher preoperative risk.

Keywords: ECE; FS; NS; NVB; PCa; PSA; PSM; RALPE; RP; RPE; extracapsular extension; frozen section analysis; frozen sections; nerve sparing; neurovascular bundle; open retropubic RP; pathology; positive surgical margin; prostate; prostate cancer; prostate specific antigen; prostatectomy; prostatic neoplasms; radical prostatectomy; robot-assisted laparoscopic RP.