Benchmarking circumferential resection margin (R1) resection rate for rectal cancer in the neoadjuvant era

Influence of incorrect staging of colorectal carcinoma on oncological outcome: are we playing safely?

Accurate preoperative staging of colorectal cancers is critical in selecting patients for neoadjuvant therapy prior to resection. Inaccurate staging, particularly understaging, may lead to involved resection margins and poor oncological outcomes. Our aim is to determine preoperative imaging accuracy of colorectal cancers compared to histopathology and define the effect of inaccurate staging on patient selection for neoadjuvant treatment(NT). Staging and treatment were determined for patients undergoing colorectal resections for adenocarcinomas in a single tertiary centre(2016-2020). Data were obtained for 948 patients. The staging was correct for both T and N stage in 19.68% of colon cancer patients. T stage was under-staged in 18.58%. At resection, 23 patients (3.36%) had involved pathological margins; only 7 of which had been predicted by pre-operative staging. However, the staging was correct for both T and N stage in 53.85% of rectal cancer patients. T stage was understaged in 26.89%. Thirteen patients had involved(R1)margins; T4 had been accurately predicted in all of these cases. There was a general trend in understaging both the tumor and lymphonodal involvement (T p < 0.00001 N p < 0.00001) causing a failure in administrating NT in 0.1% of patients with colon tumor, but not with rectal cancer. Preoperative radiological staging tended to understage both colonic and rectal cancers. In colonic tumours this may lead to a misled opportunity to treat with neoadjuvant therapy, resulting in involved margins at resection.

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.

The Importance of the Pathologist's Role in Assessment of the Quality of the Mesorectum

Total mesorectal excision (TME) is considered standard of care for rectal cancer treatment. Failure to remove the mesorectal fat envelope entirely may explain part of observed local and distant recurrences. Several studies suggest quality of the mesorectum after TME surgery as determined by pathological evaluation may influence prognosis. We aimed to determine the prognostic value of the plane of surgery as well as factors influencing the likelihood of a high-quality specimen by reviewing the literature. A pooled meta-analysis of relevant outcome data was performed where appropriate. A muscularis propria resection plane was found to increase the risk of local recurrence (RR 2.72 [95 % CI 1.36 to 5.44]) and overall recurrence (RR 2.00 [95 % CI 1.17 to 3.42]) compared to an (intra)mesorectal plane. Plane of surgery is an important factor in rectal cancer treatment and the documentation by pathologists is essential for the improvement of TME quality and patient outcome.

The Importance of the Pathologist's Role in Assessment of the Quality of the Mesorectum

Total mesorectal excision (TME) is considered standard of care for rectal cancer treatment. Failure to remove the mesorectal fat envelope entirely may explain part of observed local and distant recurrences. Several studies suggest quality of the mesorectum after TME surgery as determined by pathological evaluation may influence prognosis. We aimed to determine the prognostic value of the plane of surgery as well as factors influencing the likelihood of a high-quality specimen by reviewing the literature. A pooled meta-analysis of relevant outcome data was performed where appropriate. A muscularis propria resection plane was found to increase the risk of local recurrence (RR 2.72 [95 % CI 1.36 to 5.44]) and overall recurrence (RR 2.00 [95 % CI 1.17 to 3.42]) compared to an (intra)mesorectal plane. Plane of surgery is an important factor in rectal cancer treatment and the documentation by pathologists is essential for the improvement of TME quality and patient outcome.

MRI-based indications for neoadjuvant radiochemotherapy in rectal carcinoma: interim results of a prospective multicenter observational study

BACKGROUND

This study evaluated use of circumferential resection margin status in preoperative MRI (mrCRM) as an indication for neoadjuvant radiochemotherapy (nRCT) in rectal carcinoma patients.

MATERIALS AND METHODS

In a multicenter prospective study, nRCT was given to patients with carcinoma of the middle rectum with positive mrCRM (≤1 mm), with cT3 low rectal carcinoma, and all patients with cT4 tumors. The short-term endpoints were pathologic pCRM (≤1 mm) as a strong predictor of local recurrence rate and the quality of total mesorectal excision according to the plane of surgery. These endpoints were compared in patients with and without nRCT.

RESULTS

Of 230 patients that met the inclusion criteria, 96 (41.7%) received a long course of nRCT and 134 (58.3%) were primarily operated on. The pCRM was positive in 13 of 230 (5.7%) (primarily operated on, 2 of 134 [1.5%]; after nRCT, 11 of 96 [11%]). In 1 of 134 (0.7%) case, the mrCRM was falsely negative. Patients at participating centers varied in terms of preoperative stage but not in pCRM positivity (0%-13%, P = .340). The plane of surgery was mesorectal (good) in 209 of 230 (90.9%), intramesorectal (moderate) in 16 of 230 (7%), and the muscularis propria plane (poor) in 2.2% (5 of 230).

CONCLUSIONS

Low pCRM positivity and the high quality of mesorectal excision support use of MRI-based nRCT in rectal carcinoma. nRCT was avoidable in 45% of patients with stage II and III disease without significant risk of undertreatment. Preoperative MRI thus allows identification of patients with high risk of local recurrence and use of selective nRCT.