The impact of the nodal status on the overall survival of non-surgical patients with esophageal squamous cell carcinoma

BACKGROUND: The prognosis of N categories for patients with non-surgical esophageal carcinoma based on the number of metastatic lymph nodes is controversial. The present study analyzes prognostic implications of the number, extent, and size of metastatic lymph nodes for patients with esophageal squamous cell carcinoma (ESCC) treated with definitive (chemo-)radiotherapy to provide more information on treatment strategy. METHODS: We reviewed 357 ESCC patients treated with definitive radiotherapy between January 2013 and March 2016 retrospectively. We assessed potential associations between the involved extent (N0, 1 region, 2 regions, and 3 regions), number (N0, 1–2, 3–6, and ≥ 7), and size (N0, ≤2 cm, and > 2 cm) of metastatic lymph nodes and overall survival. Multivariate analyses of the clinicopathological factors were performed using the Cox proportional hazard model. RESULTS: 5-year survival rates were 43.6% for patients in the N0 group and 29.3% in the N+ group (p = 0.001). Kaplan-Meier analyses for all cases revealed that there were significant differences in survival based on the extent (the OS rates at 3 years were 53.3% for patients in the N0 group, 45.7% in the 1 region-involved group, 28.0% in the 2 regions-involved group, and 13.3% in the 3 regions-involved group, P < 0.001), number (the OS rates at 3 years were 49.0% for patients in the 1–2 LNs group, 27.8% in the 3–6 LNs group, 0 in the ≥7LNs group, P < 0.001), and size (the OS rates at 3 years were 41.6% for patients in the LNs ≤2 cm group and 20.7% in the LNs > 2 cm group, P = 0.001) of metastatic LNs. One hundred seventy-two patients (48.2%) had experienced GTV failure, 157 (43.1%) had distant failure, 49 (13.7%) had out-of-GTV nodal failure, and 70 patients (19.6%) had no evidence of disease at the last follow-up. Nodal status correlated statistically with GTV failure. Patients with LN metastases in the abdominal region had worse survival rates than those with metastases in the other regions. The extent and number of metastatic LNs, T category, Primary tumor location, and chemotherapy were independent prognostic factors of OS in multivariate analyses. CONCLUSIONS: For patients with ESCC who received definitive (chemo-)radiotherapy, the number, extent, and size of metastatic LNs were prognostic factors, particularly of the T2/3 disease. Patients with LN metastases in the abdominal region had worse survival.