430. PROGNOSTIC PATTERNS OF LYMPH NODES WITH COMPLETE TREATMENT RESPONSE IN ESOPHAGEAL SQUAMOUS CELL CARCINOMA AFTER NEOADJUVANT CHEMORADIOTHERAPY AND NEOADJUVANT CHEMOTHERAPY

Abstract Background The prognostic significance of lymph nodes with pathological complete treatment response (pcr-LN) has not been well investigated in esophageal squamous cell carcinoma (ESCC). We aimed to determine the prognostic impact of pcr-LNs in ESCC after either neoadjuvant chemoradiotherapy (nCRT) or neoadjuvant chemotherapy (nCT). Methods 578 patients with ESCC from two medical facilities were analyzed retrospectively, with 303 patients receiving nCRT and 275 receiving nCT. Pcr-LNs were defined as LNs exhibiting regression changes, such as fibrosis, mucin lakes, keratinization, and giant cell responses but no evidence of living tumor cells. 5 LN status subgroups were identified based on the ypN category in 8th AJCC: ypN0/pcr-LN-, ypN0/pcr-LN+, ypN1, ypN2, and ypN3. The Kaplan-Meier approach was used to analyze the overall survival (OS), and subgroup findings were compared using the log-rank test. Multivariate analysis of OS was performed using a Cox proportional hazard model. Results 45 patients were classified into ypN0/pcr-LN+ (7.8%), 33 in the nCRT group, and 12 in the nCT group (p = 0.006). Compared to the nCRT group, the nCT group underwent a more thorough LN dissection (LN (mean (SD)): nCRT, 21.05 (8.77); nCT, 26.08 (11.66); p = 0.001). Survival analysis of OS showed the subgroup ypN0/pcr-LN+ had a significantly worse prognosis than ypN0/pcr-LN- in the nCRT group (p = 0.047), but no difference was seen in the nCT group. Multivariable analysis revealed that ypN0/pcr-LN+ patients in the nCRT group had a greater risk of mortality than ypN0/pcr-LN- patients (p = 0.0487). Conclusion The nCRT group had a more noticeable complete treatment response in LNs than the nCT group. However, in comparison to the nCT group, the nodal downstaging with radiotherapy in the nCRT group may not translate into improved outcomes. More aggressive systemic therapy might be required to improve the overall survival in esophageal cancer patients receiving neoadjuvant treatment.