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THE RELATIONSHIP BETWEEN MESORECTAL GRADING AND ONCOLOGIC OUTCOMES IN RECTAL ADENOCARCINOMA
Jorge Silva Velazco*, Luca Stocchi, Michael Valente, James M. Church, David Liska, Emre Gorgun, Matthew Kalady, Hermann Kessler, Scott R. Steele, Conor P. Delaney
Cleveland Clinic, Cleveland, OH
Purpose: To determine the impact of mesorectal grading on oncologic outcomes in patients undergoing TME with curative intent for rectal adenocarcinoma in a specialized unit.
Methods: Patients from a prospectively-maintained database with clinical stage I-III rectal adenocarcinoma undergoing curative intent TME between 2010 and 2014 were included. We compared rates of local and distant recurrence, disease-free and overall survival in patients with complete mesorectum (CM), near complete mesorectum (NCM) and incomplete mesorectum (IM). We also assessed mesorectal grading as an independent factor associated with oncologic outcomes using Kaplan-Meier analyses and multivariate models also including other relevant factors selected with a stepwise process.
Results: Out of 440 patients, 292 were male (66%), median age at resection was 60 (29-93) and 300 (63%) underwent restorative procedures. There were 395 (89.8%), 28 (6.4%) and 17 (3.9%) patients with CM, NCM and IM, respectively. After a mean follow-up of 2 ± 1.3 years, 62 (14.1%) patients were deceased, 9 (2%) patients developed local recurrence and 30 (6.8%) had distant recurrence, respectively. Mesorectal grading groups were similar in patient age and gender, ASA score, neoadjuvant treatment use, clinical and pathology stage, tumor size, lymph node harvest, and distal margin involvement rates (all p>0.05). CM was more commonly associated with restorative procedures (p<0.01), longer tumor distance from the anal verge (p=0.01), moderate differentiation (p=0.006) and uninvolved radial margins (p<0.001). Unadjusted 3-year Kaplan-Meier oncologic outcomes by mesorectal grade are shown in the table. BMI was not associated with oncologic outcomes on univariate analysis and was excluded from stepwise regression. Factors included in the multivariate models along with mesorectal grades were surgical approach (open, laparoscopic or robotic), stage (I, II, III or complete pathologic response), radial margin involvement, use of neoadjuvant treatment, age at resection, gender, previous abdominal surgery, ASA score, diabetes mellitus, hypertension, cardiac or renal comorbidities. IM was an independent factor associated with decreased overall survival [HR 0.28 (95% CI, 0.1-0.82; p=0.02] and NCM was independently associated with decreased disease-free survival [HR 0.49 (95% CI, 0.24-0.99; p=0.04]. There were no associations between mesorectal grading and overall, local, or distant recurrence (p= 0.84, p=0.38 and p=0.4, respectively).
Conclusions: The prognostic value of mesorectal grading for recurrence after rectal cancer resection in a specialized unit was limited. Mesorectal grading had a stronger prognostic value for mortality unrelated to rectal cancer. Future studies should elucidate this unexpected relationship.
Unadjusted Kaplan-Meier estimates of oncologic outcomes at 3 years following resection according to mesorectal grade
| 3-year oncologic outcomes, % | CM (n = 395) | NCM (n = 28) | IM (n = 17) | p | | Overall Survival | 84.8% | 49.9% | 71.7% | <0.001 | | Disease Free Survival | 79.8% | 45.9% | 71.7% | <0.001 | | Overall Recurrence | 11.4% | 24.7% | 0% | 0.59 | | Local Recurrence | 2.5% | 10% | 0% | 0.25 | | Distant Recurrence | 10% | 15.3% | 0% | 0.57 |
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