Background: Microscopic cancer spreading to extranodal connective tissues (extranodal spreading: ENS) is occasionally found in resected specimens from patients with esophageal squamous cell carcinoma (SCC), but the prognostic impact of ENS remains unclear. The aims of this study were to elucidate the prognostic impact of ENS to help determine the most suitable management for the patients with ENS.
Methods: We histologically re-evaluated 7,349 lymph nodes obtained from 171 patients with SCC of the thoracic esophagus who underwent potentially curable resection between 1992 and 2003. We defined ENS as microscopic penetration of tumor cells from metastatic lymph nodes or tumor cell dissemination into extranodal connective tissues.
Results: Extranodal spreading was found in 37 (21.6%) patients, and it had a significant relationship with diameter and depth of the tumor, lymphatic and venous invasion, intramural metastasis, and number of metastatic nodes. Patients who were ENS positive were at higher risk of recurrence, and their overall survival rate was lower than that for ENS-negative patients. Furthermore, recurrent risk was higher and overall survival rate was lower in ENS-positive patients than in ENS-negative patients when they had 1-3 metastatic nodes, but recurrent risk and overall survival rate of the patients with 4 or more metastatic nodes were very similar in ENS-positive and ENS-negative patients.
Conclusions: The present findings suggest that in SCC of the thoracic esophagus, the presence of ENS increases recurrent risk and reduces the overall survival of the patients with 1-3 metastatic nodes. Patients showing ENS should be managed in the same way as patients with 4 or more metastatic nodes.