Prediction of prognosis by the extent of lymph node involvement in squamous cell carcinoma of the thoracic esophagus

Objectives: Current criteria of the N-category in the TNM staging system for carcinoma of the esophagus needs further subgrouping due to its simplicity in mixing together patients with different prognosis. Method: A retrospective cohort study of 186 patients (176 men and ten women; mean age, 59.9 years) with squamous cell carcinoma (SCC) of the thoracic esophagus who underwent esophagectomy followed by two-field lymphadenectomy and cervical lymph node sampling between 1992 and 1999 was conducted. A proposed N-category which involved dividing the nodal status into N0 (no nodal involvement), N1 (≤4 nodes or ≤20% nodal involvement), and N2 (>4 nodes, or >20%, or non-regional nodal involvement) subgroups was used for survival analysis. Results: The overall 5-year cumulative survival rate was 27%. Lymph node metastases were identified in 101 (54.3%) patients. Cumulative survival rates were 46% at 4 years in the N0 group and 21% at 4 years in the N1 group, whereas no patients in N2 group survived longer than 3 years (P<0.01). A multivariable analysis revealed that independent prognostic factors included the depth of tumor invasion (P<0.01), nodal involvement (P<0.01), and organ metastasis (P<0.01). Conclusion: In addition to the location of nodes, the extent of nodal involvement in SCC of the thoracic esophagus also plays an important role in prognosis prediction.