e15555 Background: Surgery is the most important treatment for patients with lower thoracic esophageal squamous cell carcinoma (LT-ESCC) at stage III, but the locoregional failure is common, especially mediastinal and supraclavicular lymph nodes metastases. Postopearative radiotherapy (PORT) is benefit for those patients. However, the clinic target volume (CTV) remains controversial, especially whether or not including bilateral supraclavicular lymph nodes radiotherapy. Methods:79 patients of lower LT-ESCC at stage III who had undergone radical surgery and PORT were enrolled. 51 patients received the PORT CTV without bilateral suparclavicular lymph nodes region (group A), while 28 patients received the CTV with suparclavicular region (group B). Results: Totally, 26 patients had the tumor recurrences of supraclavicular lymph nodes. Among them, 23(45.1%) patients had the metastasis in group A, 3(10.7%) patients had the metastasis in group B. Univariate analysis showed the bilateral supraclavicular region RT can decrease of supraclavicular lymph nodes recurrence (p = 0.007). However, it could not prolong the overall survival (p = 0.273) or control the distant metastasis (p = 0.760).The Cox analysis revealed it was independent factor to control supraclavicular lymph node recurrence (HR = 0.027; 95 % CI 0.068-0.757; p = 0.016). PORT includingsupraclavicular region didn’t increase the radiotherapy complications, such as radiation pneumonia (p = 0.354), radiation esophagitis (p = 0.456), gastrointestinal reaction (p = 0.809), neutropenia (p = 0.470), thrombocytopenia (p = 0.137) and anemia (p = 0.642). Conclusions:PORT including bilateral supraclavicular region can reduce the metastasis of supraclavicular lymph nodes in LT-ESCC at stage III, and it does not increase radiotherapy complications. However, it can’t prolong OS or control the distant metastasis. Chemotherapy is essential to control distant metastasis and prolong OS.