Objective: To analyze the patterns of the first sites of failure in patients with clinical stage I thoracic esophageal cancer after involved field radiotherapy and to determine whether elective nodal irradiation is necessary for these patients.
Materials and methods: Between 2000 and 2007, 68 patients aged 43-84 years with clinical stage I thoracic esophageal cancer received definitive radiotherapy. The radiation field included the primary tumor with a 3-cm margin in the cranio-caudal direction. Patterns of lymph node failure were classified according to the first sites of failure. In-field, regional and distant lymph node failures were defined as lymph node failures within the irradiated area, within the mediastinum or perigastric area beyond the irradiated area, and outside the regional lymph nodes, respectively.
Results: The 3 year overall and disease-free survival rates were 76 and 66%, respectively (median follow-up: 42 months). Twenty-two of the 68 patients exhibited treatment failure. Local failure with or without recurrence in other sites was observed in 11 patients, lymph node failure in 10 patients, and distant metastasis in 1. Of the 10 patients with lymph node failure, sites of failure were in-field in 1 patient, in-field and distant in 1, regional in 3, distant in 2 and distant and regional in 3.
Conclusions: Involved field radiotherapy did not result in significant incidence of regional lymph node failure in clinical stage I thoracic esophageal cancer patients. However, further investigation is needed to establish the optimal radiotherapy field for clinical stage I thoracic esophageal cancer.