eP507 - Where Are We with Endoscopic Resection for Clinical Stage I Rectal Cancer? A National Cancer Database Analysis

Purpose/Background: It remains unclear how accurate we are at predicting pathologic status (pTxNx) for early-stage rectal cancers based on clinical data and staging. We hypothesize that the National Cancer Database (NCDB) could elucidate practice patterns and outcomes to better guide optimal management for Stage I patients.Methods/Interventions: Retrospective analysis was performed of patients with Stage 1 (cT1N0 and cT2N0) rectal adenocarcinoma between 2004-2020 from the NCDB who underwent endoscopic local tumor resection (ER) or surgical resection (SR). We analyzed demographics, clinical and pathologic staging, adjuvant therapy, and survival data. Pearson Chi-Squared tests, Bonferroni post-hoc analysis, and Kaplan-Meier survival analysis were performed.Results/Outcomes: 21,133 patients were included. The mean patient age was 64.1 years, 58.9% were male and 87.0% were Caucasian. 5,248 patients underwent ER and 15,885 underwent SR. Patients who underwent ER were significantly older (mean age 67.2 years vs 63.1 years in SR group, p < 0.001) and had significantly higher Carlson-Deyo Comorbidity Index Score (p=0.03). 3.6% of ER patients had pathologic T stage upstaging, compared to 24.7% in those undergoing SR (p < 0.01). 22.6% of SR patients were found to have pathologic nodal disease; 17.1% with pN1 disease and 5.5% and pN2 disease. cT2N0 patients who underwent surgical excision were more likely to be upstaged and have pathologic nodal disease compared to those with cT1N0 disease (23.3% vs. 21.5%; p=0.011). 25.6% of ER patients received adjuvant radiation and/or chemotherapy, compared to 42.5% who underwent SR (p < 0.001). Overall survival at 5 years was lower in ER group compared to the SR group (75.3% vs. 79.5%; p < 0.001, Figure 1). When stratified by original clinical tumor stage, those who with cT2 disease who underwent endoscopic resection had the significantly lowest overall survival (p < 0.001, Figure 2; 5 year OS 67.6% (cT2 ER) vs. 78.9% (cT2 SR), 79.3% (cT1 ER), 80.6% (cT1 SR)).Conclusion/

Discussion: In patients with clinical Stage I rectal cancer treated by ER compared to SR, differences were identified in demographics, pathologic staging, adjuvant therapy trends, and overall survival. Patients who underwent SR were upstaged by pathology T stage significantly more compared to ER patients (24.7% vs 3.6%, p < 0.001). Patients who underwent SR were upstaged by pathologic N stage 22.6% of time. As pathologic nodal disease is not evaluated in those who undergo ER, this may reflect a large proportion of patients in the ER cohort who are possibly understaged. This is particularly relevant, as ER patients received adjuvant therapy significantly less than the SR group (25.6% vs 42.5%, p < 0.001). This could possibly reflect undertreatment in an understaged cohort. This is reflected in the survival data, where OS for ER patients was less favorable over time compared to SR (p < 0.001). Thus, it is not yet clear whether ER is equivalent to SR for early-stage rectal cancer."Figure 1. Overall Survival in Clinical Stage I (cT1/cT2N0) Rectal Adenocarcinoma treated by Endoscopic Resection compared to Surgical Resection

Figure 2. Overall Survival in Stage I Rectal Adenocarcinoma treated by in cT1N0 and cT2N0 Endoscopic Resection compared to cT1N0 and cT2N0 Surgical Resection
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