311 PATHOLOGIC COMPLETE LYMPH NODE REGRESSION AFTER NEOADJUVANT CHEMORADIOTHERAPY FOR ESOPHAGEAL SQUAMOUS CELL CARCINOMA

Abstract

Abstract Pathologic complete lymph node regression, which is defined as lymph nodes with evidence of neoadjuvant treatment effect but without viable residual cancer cells, are sometimes observed following neoadjuvant treatments and has been shown to be prognostic, yet with conflicting results. We aim to study its clinicopathological correlation and prognostic impact. Methods Patients who received neoadjuvant chemoradiotherapy (nCRT) followed by esophagectomy for esophageal squamous cell carcinoma (ESCC) in a single institute are retrospectively reviewed. Lymph nodes retrieved at post-nCRT esophagectomy are re-examined by a dedicated pathologist. Patients are classified as (1) lymph node-negative with no evidence of tumor involvement or regression (true negative; plausible cN0, ypN0; group 1); (2) lymph node-negative with evidence of complete regression (e.g. fibrosis; plausible cN+ ypN0; group 2); and (3) lymph node-positive (ypN+; group 3). Kaplan–Meier curve and log-rank test, and cumulative incidence of recurrence (CIR) are used for outcome analysis. Results A total of 136 patients, including 73, 25, and 38 in group 1, 2, and 3, respectively, are included. Group 2 is significantly associated with lower risk for lymphovascular invasion (0%, p < 0.001) and perineural invasion (4%, p = 0.038), and higher rate of pathologic complete response in primary tumor (76%, p < 0.001). The 5-year overall survival rates in group 1, 2, and 3 are 42.1%, 52.8%, and 8.0%, respectively. There is no survival difference between group 1 and 2 (p = 0.454). The CIR at 24 months are 46% and 41% in group 1 and 2 (HR: 0.84, 95% CI: 0.432–1.623, p = 0.601, figure 1). Conclusion Pathologic complete lymph node regression correlates with treatment response in primary tumor. The outcome of patients with pathologic complete lymph node regression is comparable to that of those with true negative lymph node involvement. Pathologic complete lymph node regression could be a surrogate for chemoradiotherapy sensitivity and regarded as a good prognostic factor in patients with ESCC.