Pathological tumor regression grade of metastatic tumors in lymph node predicts prognosis in esophageal cancer patients

Tumor regression grade of the primary tumor (TRG‐PT) and residual lymph node metastasis have been pathologically determined in esophageal squamous cell carcinoma (ESCC) patients who had received neoadjuvant chemotherapy (nCT) followed by surgery; however, TRG of the metastatic tumor involving lymph nodes (LN) has not yet been determined. The aim of the present study was to clarify the impact of TRG on the prognosis of ESCC patients. ESCC patients (n = 110) who had received nCT followed by surgery were enrolled. Dissected LN were classified into 2 categories: plausible positive metastatic LN (pp‐MLN) where viable and/or degenerated ESCC cells and/or tissue modifications were observed, and non‐metastatic LN (non‐MLN) where neither of them was observed. We defined nCT‐effective rate (CER) as the ratio of the number of pp‐MLN that showed tumor regression to the total number of pp‐MLN, and divided CER into low‐CER (LCER; ≥0% and <50%) and high‐CER (HCER; ≥50% and ≤100%). Relationships between CER and clinicopathological factors including prognosis were then examined. Multivariate analyses of 110 patients indicated that ypT3‐4 (P = .023, HR; 2.551), positive venous infiltration (P = .006, HR; 3.526), and LCER (P = .033, HR; 1.922) were independently associated with shorter recurrence‐free survival (RFS). Multivariate analyses of 43 patients with grade 0 TRG‐PT showed that ypT3‐4 (P = .033, HR; 3.397) and LCER (P = .008, HR; 3.543) were independently associated with shorter RFS. This study showed that CER was one of the prognostic factors for ESCC patients who had received nCT followed by surgery.