Plane of mesocolic dissection as predictor of recurrence after complete mesocolic excision for sigmoid colon cancer: A cohort study

Abstract

Aim: To investigate whether intramesocolic plane dissection assessed on fresh specimens by the pathologist is a risk factor for recurrence after complete mesocolic excision for sigmoid cancer when compared with mesocolic plane dissection.

Method: Single-centre study based on prospectively registered data on patients undergoing resection for UICC stage I-III sigmoid colon adenocarcinoma during the period 2010-2017. The patients were stratified into either an intramesocolic plane group or a mesocolic plane group. Primary outcome was risk of recurrence after 4.2 years using inverse probability treatment weighting and competing risk analyses.

Results: Of a total of 332 patients, two were excluded as the specimen was assessed as muscularis propria plane, 237 (72%) specimens were deemed as mesocolic and 93 (28%) as intramesocolic. The 4.2-year cumulative incidence of recurrence after inverse probability treatment weighting was 14.9% (10.4-19.3) in the mesocolic group compared with 9.4% (3.7-15.0) in the intramesocolic group, thus the absolute risk difference between the mesocolic plane and intramesocolic plane was 5.5% (-12.5-1.6; p = 0.13) in favour of the intramesocolic group.

Conclusion: Intramesocolic plane dissection was not a risk factor for recurrence after complete mesocolic excision for sigmoid cancer when compared with mesocolic plane dissection. No difference in risk of local recurrence, death before recurrence, and in overall survival after 4.2 years was observed between the two groups. With less than 1% of the specimens deemed as muscularis propria plane dissection, the classification appears unusable for the risk prediction of sigmoid colon cancer.

Keywords: colon cancer; mesocolic dissection plane; recurrence; sigmoid colon.

FIGURE 1

Photographs of specimen after left hemicolectomy for sigmoid cancer and adenoma in the proximal descending colon (not shown). (A) Anterior aspect of the mesocolon. The tumour in the distal part of the sigmoid colon is marked with an arrow. The vascular structures are shown, and the avascular window in the mesocolon cranial to the sigmoid vessels demarcates the area to be assessed. The inferior mesenteric artery (IMA) is marked with a white clip. (B) Posterior/medial aspect of the mesocolon. The tumour in the distal part of the sigmoid colon is marked with an arrow. The apposed mesocolon is shown. (C) Posterior/medial aspect of the mesocolon. The area to be assessed for mesocolic plane dissection assessment is marked with green, in this case assessed as mesocolic plane dissection

FIGURE 2

Flowchart of patient selection. CME, complete mesocolic excision; UICC, Union for International Cancer Control

FIGURE 3

4.2‐year cumulative incidences of recurrence, local recurrence and death before recurrence in patients undergoing complete mesocolic excision for UICC stages I–III sigmoid colon cancer during 2010–17 using unadjusted data and stratified by dissection plane assessed by the pathologists. Shaded areas are 95% CIs. (A) Cumulative incidence of recurrence in patients undergoing resection between 2010 and 2017. (B) Cumulative incidence of local recurrence in patients undergoing resection between 2010 and 2017. (C) Cumulative incidence of death before recurrence in patients undergoing resection between 2010 and 2017

FIGURE 4

Overall mortality of patients with UICC stages I–III colon sigmoid cancer undergoing elective surgery between 2010 and 2017 stratified by dissection plane assessed by the pathologists. Shaded areas are 95% CIs