Efficacy and utility of intraoperative frozen section analysis in robot assisted radical prostatectomies: What should pathologists and urologists know?

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Conference Proceeding

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Lab Invest


Background: Preservation of sphincter integrity and neurovascular bundles with negative resection margins in Radical Robot Assisted Prostatectomy (RARP) is a challenge. Nerve sparing leads to higher rates of positive surgical margins (PSMs), which an independent risk factor for biochemical recurrence. Intraoperative frozen section (IFS) is used to balance these goals by lowering PSMs. In this study, utility and efficacy of IFS was investigated. Design: Data and pathology slides of 99 patients undergoing IFS during RARP in 2015 were analyzed. Anatomical site of IFS was noted and compared with corresponding paraffin sections and final margins (FMs) of main prostatectomy specimen, divided into 6 categories (C) and analyzed (Table 1). IFS site was compared with previous biopsy findings. Results: We retrieved 99 patients, who had IFS during RARP, of which most were of low stage and grade (57% Grade Group 1 or 2 and 58% pT2) (Table 2). IFS was positive for carcinoma in 12 patients (13%), 2 of which were reinterpreted as negative on paraffin sections (C4). Negative IFS in 3 cases was reinterpreted as positive on paraffin sections (C1). The remainder 93 were concordant with concordance rate of 95%. IFS helped in getting negative FM in 76 (78%) patients in C3 and C6 who then underwent nerve sparing RARP. In 4 patients of C6, IFS converted a positive to negative FM. Out of these 4, 3 had high Grade Groups of 4 and 5. The rest of 22 (25%) cases in C2 and C5 had positive FM in spite of IFS. C2 and C5 had cases with higher stage, EPE and SV invasion as compared to C3. IFS site matched previous biopsy tumor location in 75 patients, out of which 19 had positive FM. IFS site did not match in 13 cases of whom 7 had positive FM. Conclusions: We found high concordance between frozen and corresponding paraffin sections. IFS was useful in majority of patients (78%), particularly in 4 patients of C6 where a positive was converted into negative FM, 3 of whom had high Grade Groups. Thus, IFS might be of greater value in reducing PSM in patients with higher grades. IFS failed to achieve negative FM in 22 cases (25%). Of these 22, 13 (60%) were higher stage. Extensive sampling and multiple IFS may be necessary to reduce PSM in higher stage tumors. Significant difference in rate of PSM between patients who had matched IFS and previous biopsy tumor location and unmatched cases (19/75 versus 7/13) was noted. Better correlation between IFS site and previous biopsy findings might lower PSM rate.



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