A comparison of whole-mount and conventional sections for pathological mesorectal extension and circumferential resection margin assessment after total mesorectal excision

Francisco Giner; Matteo Frasson; Hanna Cholewa; Jorge Sancho-Muriel; Enrique García-Gómez; Josselyn A Hernández; Blas Flor-Lorente; Eduardo García-Granero

doi:10.1016/j.cireng.2024.01.008

A comparison of whole-mount and conventional sections for pathological mesorectal extension and circumferential resection margin assessment after total mesorectal excision

Cir Esp (Engl Ed). 2024 Feb 17:S2173-5077(24)00049-8. doi: 10.1016/j.cireng.2024.01.008. Online ahead of print.

Authors

Francisco Giner¹, Matteo Frasson², Hanna Cholewa³, Jorge Sancho-Muriel³, Enrique García-Gómez⁴, Josselyn A Hernández⁴, Blas Flor-Lorente⁵, Eduardo García-Granero⁶

Affiliations

¹ Pathology Department, University of Valencia, Valencia, Spain; Pathology Department, Hospital Universitari I Politècnic La Fe, Valencia, Spain.
² Coloproctology Unit, Hospital Universitari I Politècnic La Fe, University of Valencia, Valencia, Spain; Surgery Department. University of Valencia, Spain. Electronic address: Matteo.Frasson@uv.es.
³ Coloproctology Unit, Hospital Universitari I Politècnic La Fe, University of Valencia, Valencia, Spain.
⁴ Pathology Department, Hospital Universitari I Politècnic La Fe, Valencia, Spain.
⁵ Coloproctology Unit, Hospital Universitari I Politècnic La Fe, University of Valencia, Valencia, Spain; Surgery Department. University of Valencia, Spain.
⁶ Surgery Department. University of Valencia, Spain.

PMID: 38373616
DOI: 10.1016/j.cireng.2024.01.008

Abstract

Introduction: The objective of the study is to compare 2 techniques for histological handling of rectal cancer specimens, namely whole-mount in a large block vs conventional sampling using small blocks, for mesorectal pathological assessment of circumferential resection margin status and depth of tumor invasion into the mesorectal fat.

Methods: This is a prospective study including 27 total mesorectal excision specimens of rectal cancer from patients treated for primary rectal carcinoma between 2020 and 2022 in a specialized multidisciplinary Colorectal Unit. For each total mesorectal excision specimen, 2 contiguous representative tumoral slices were selected and comparatively analyzed with whole-mount and small blocks macroscopic dissection techniques, enabling comparison between them in the same surgical specimen. The agreement between the 2 techniques to assess the distance of the tumor from the circumferential resection margin as well as the depth of tumor invasion was evaluated with the Student's t-test for paired samples, Pearson's correlation coefficient, and the Bland-Altman method comparison analysis.

Results: Complete mesorectal excision was observed in 8% of cases. Circumferential resection margin involvement was observed in only one case (4 %). The whole-mount and small block techniques obtained similar results when we assessed the distance to the circumferential resection margin (t-test P = 0.8, r = 0.92) and the depth of mesorectal infiltration (t-test P = 0.6, r = 0.95).

Conclusions: Both gross dissection techniques (whole-mount vs multiple small cassettes) are equivalent and reliable to assess the distance to circumferential resection margin and the depth of mesorectal infiltration in the mesorectal fat in rectal cancer staging.

Keywords: Carcinoma de recto; Carcinoma of rectum; Circumferential resection margin; Conventional dissection; Disección convencional; Margen de resección circunferencial; Sección “whole-mount”; Whole-mount section.