The Relationship Between Mesorectal Grading and Oncological Outcome in Rectal Adenocarcinoma

Aim: The prognostic association between mesorectal grading and oncological outcome in patients undergoing resection for rectal adenocarcinoma is controversial. The aim of this retrospective chart review was to determine the individual impact of mesorectal grading on rectal cancer outcomes.

Method: We compared oncological outcomes in patients with complete, near-complete and incomplete mesorectum who underwent rectal excision with curative intent from 2009 to 2014 for Stage cI-III rectal adenocarcinoma. We also assessed the independent association of mesorectal grading and oncological outcome using multivariate models including other relevant variables.

Results: Out of 505 patients (339 men, median age of 60 years), 347 (69%) underwent a restorative procedure. There were 452 (89.5%), 33 (6.5%) and 20 (4%) patients with a complete, near-complete and incomplete mesorectum, respectively. Local recurrence was seen in 2.4% (n = 12) patients after a mean follow-up of 3.1 ± 1.7 years. Unadjusted 3-year Kaplan-Meier analysis by mesorectal grade showed decreased rates of overall, disease-free and cancer-specific survival and increased rates of overall and distant recurrence with a near-complete mesorectum, while local recurrence was increased in cases of an incomplete mesorectum (all P < 0.05). On multivariate analyses, a near-complete mesorectum was independently associated with decreased cancer-specific survival (hazard ratio 0.26, 95% CI 0.1-0.7; P = 0.007). There were no associations between mesorectal grading and overall survival, disease-free survival, overall recurrence or distant recurrence (all P > 0.05).

Conclusion: Mesorectal grading is independently associated with oncological outcome. It provides unique information for optimizing surgical quality in rectal cancer.