Postoperative MRI Findings Following Conventional and Extralevator Abdominoperineal Excision in Low Rectal Cancer.

Kim Morgenstjerne Oerskov,Henrik Lauridsen,Bodil Ginnerup Pedersen,Søren Laurberg,Rikke H Hagemann-Madsen,Henrik Kidmose Christensen,Peter Bondeven

doi:10.3389/fsurg.2021.771107

Abstract

Aim: The disparity in outcomes for low rectal cancer may reflect differences in operative approach and quality. The extralevator abdominoperineal excision (ELAPE) was developed to reduce margin involvement in low rectal cancers by widening the excision of the conventional abdominoperineal excision (c-APE) to include the posterior pelvic diaphragm. This study aimed to determine the prevalence and localization of inadvertent residual pelvic diaphragm on postoperative MRI after intended ELAPE and c-APE.Methods: A total of 147 patients treated with c-APE or ELAPE for rectal cancer were included. Postoperative MRI was performed on 51% of the cohort (n = 75) and evaluated with regard to the residual pelvic diaphragm by a radiologist trained in pelvic MRI. Patient records, histopathological reports, and standardized photographs were assessed. Pathology and MRI findings were evaluated independently in a blinded fashion. Additionally, preoperative MRIs were evaluated for possible risk factors for margin involvement.Results: Magnetic resonance imaging-detected residual pelvic diaphragm was identified in 45 (75.4%) of 61 patients who underwent ELAPE and in 14 (100%) of 14 patients who underwent c-APE. An increased risk of margin involvement was observed in anteriorly oriented tumors with 16 (22%) of 73 anteriorly oriented tumors presenting with margin involvement vs. 7 (9%) of 74 non-anteriorly oriented tumors (p = 0.038).Conclusion: Residual pelvic diaphragm following abdominoperineal excision can be depicted by postoperative MRI. Inadvertent residual pelvic diaphragm (RPD) was commonly found in the series of patients treated with the ELAPE technique. Anterior tumor orientation was a risk factor for circumferential resection margin (CRM) involvement regardless of surgical approach.

Highlights

Treatment of patients with rectal cancer has improved dramatically with the adoption of mesorectal excision surgery [1,2,3,4], the introduction of MRI for preoperative tumor staging [5,6,7], multidisciplinary team (MDT) conferences for the planning of treatment [8], and use of preoperative chemoradiotherapy (CRT)
We aimed to investigate the prevalence and localization of inadvertent residual pelvic diaphragm (RPD) on postoperative MRI after extralevator APE” (ELAPE) and c-abdominoperineal excision (APE)
All 14 patients treated with conventional APE (c-APE) had RPD in both posterior quadrants of the pelvis on postoperative MRI (Figure 4)

Summary

Introduction

Treatment of patients with rectal cancer has improved dramatically with the adoption of mesorectal excision surgery [1,2,3,4], the introduction of MRI for preoperative tumor staging [5,6,7], multidisciplinary team (MDT) conferences for the planning of treatment [8], and use of preoperative chemoradiotherapy (CRT). The observed inferior outcomes in low rectal cancer are most likely multifactorial, including high rates of positive circumferential resection margin (CRM) involvement and specimen perforation. These outcomes may in part be explained on the basis of the surgical planes during resection when conventional APE (c-APE) is performed [4, 6, 7, 9,10,11]. The procedure is performed under direct vision, leaving only the most anterior parts of the levator ani in situ, and may provide the critical extra margin of protection around a locally advanced low rectal tumor

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Conclusion