The impact of treatment approach on survival among patients with clinical stage T2N0 and T3N0 rectal cancer.

e15637 Background: Treatment of early stage rectal cancer requires a multi-disciplinary approach and is often treated with curative intent surgery with use of total neoadjuvant treatment (TNT) or neoadjuvant chemoradiotherapy (nCRT) in select cases pre-operatively. In this study, we determine the various clinicopathologic factors associated with the use of these different approaches (Surgery upfront vs nCRT vs TNT) and their effect on patient survival. Methods: The National Cancer Database (NCDB) was queried for patients with clinical T2N0M0 and T3N0M0 rectal cancer between 2004-2019. Results: 36,869 patients were identified, of which about half had nCRT only while < 15% had received TNT. Patients who underwent nCRT had the highest median OS compared to those who underwent surgery only (106.8 vs 126.5 months, p < 0.001). The surgery upfront cohort had the highest proportion of patients who were seen at a facility with high/very high case volume per year quartiles (surgery: 52.5%, nCRT: 47.3%, and TNT: 48.3%, p < 0.001). The highest median age was among the surgery cohort at 69 years followed by the nCRT cohort at 64 years and TNT cohort at 61 years (p < 0.001). Amongst patients with a Charlson-Deyo co-morbidity score of 2 or more, the surgery upfront cohort had the highest proportion while the TNT cohort had the lowest (p < 0.001). Low anterior resection (LAR) was the most common procedure among all three cohorts. A multivariate logistic regression model revealed that when compared to surgery only, the nCRT (Adjusted Odds Ratio (AOR) = 1.51, p < 0.001) and TNT (AOR = 1.62, p < 0.001) were both associated with an increased likelihood of 5-year long-term survival (LTS), with TNT having a stronger association. Among the various pre-operative characteristics, patients 70 years and older, patient with normal CEA and presence of LVI were less likely to have LTS with TNT as compared to surgery upfront. On the other hand, patients with clinical T3 stage who received TNT were much more likely to have improved LTS as compared to T2 stage (Relative Risk Ratio (RRR) 16.19, p < 0.001). Conclusions: Results of our study show that patients with early stage T2N0 and T3N0 rectal cancer who underwent neoadjuvant treatment had an improved median OS compared to patients who received surgery upfront. Both nCRT and TNT were associated with an increased likelihood of long-term survival, with TNT having a stronger association particularly in the T3N0 cohort.