Assessing surgical difficulty in locally advanced mid-low rectal cancer: the accuracy of two MRI-based predictive scores.

AIM: Predicting surgical difficulty is a critical factor in the management of locally advanced rectal cancer (LARC). This study evaluated the accuracy and external validity of a recently published morphometric score to predict surgical difficulty and, additionally, proposes a new score to identify preoperatively LARC patients with a high risk of having a difficult surgery.

METHODS: This is a retrospective study based on the European MRI and Rectal Cancer Surgery (EuMaRCS) database, including patients with mid/low LARC who were treated with neoadjuvant chemoradiation therapy and laparoscopic total mesorectal excision (L-TME) with primary anastomosis. For all patients, pretreatment and restaging magnetic resonance imaging (MRI) were available. Surgical difficulty was graded as high and low based upon a composite outcome, including operative (e.g., duration of surgery) and postoperative variables (e.g., hospital stay). Score accuracy was assessed by estimating sensitivity, specificity, and area under the receiver operating characteristic curve (AROC).

RESULTS: In a total of 136 LARC patients, 17(12.5%) were graded as high surgical difficulty. The previously published score (calculated on BMI, intertuberous distance, mesorectal fat area, type of anastomosis) showed low predictive value (sensitivity:11.8%; specificity:92.4%; AROC:0.612). The new EuMaRCS score was developed using the following significant predictors of surgical difficulty: BMI>30, interspinous distance<96.4 mm, ymrT stage ≥T3b, and male sex; it demonstrated high accuracy (AROC:0.802).

CONCLUSION: The EuMaRCS score was found to be more sensitive and specific than the previous one in predicting surgical difficulty in LARC patients who are a candidate for L-TME. However, this score has yet to be externally validated. This article is protected by copyright. All rights reserved.