['Chemoradiotherapy (CRT) is an effective modality for stage I esophageal squamous cell carcinoma (ESCC). However, salvage treatments are often required even if complete response (CR) has been achieved. To this end, it is important to accurately diagnose lymph node or other organ metastatic recurrences. Note that lymph node enlargements (except metastatic recurrence) are often detected during the follow-up period after CRT. The purpose of this study was to elucidate the clinical characteristics of lymph node enlargement after CRT.', 'In this retrospective cohort study, patients diagnosed with stage I (T1 [submucosal invasion] N0M0) ESCC were treated with cisplatin and 5-fluorouracil concurrently with radiotherapy. A total of 55 patients were enrolled in the study from February 2006 to August 2011.', 'The median follow-up period was 46 months. The 3-year overall and progression-free survival rates were 90.7% and 71.2%, respectively, and the CR rate was 87.2% (48/55). Nine of the 48 CR patients were finally diagnosed with recurrences, including 7 lymph node metastases and 2 local recurrences. Lymph node enlargement was initially identified in 20 of the total 55 patients during the follow-up; 9 patients were finally diagnosed with lymph node recurrence, whereas 11 patients had benign reactive lymph node enlargement.'] Do lymph node enlargement after definitive chemoradiotherapy for clinical stage I esophageal squamous cell carcinoma?