Randomized phase II trial comparing tumor bed alone with tumor bed and elective nodal postoperative radiotherapy in patients with locoregionally advanced thoracic esophageal squamous cell carcinoma.

This study compares the outcomes of different postoperative radiation fields for locoregionally advanced thoracic esophageal squamous cell carcinoma (ESCC) patients. This is a multi-institution randomized phase II trial and noninferior study. Patients with ESCC who had undergone esophagectomy (stage T3-4N0-3M0) were enrolled and randomized into the large-field irradiation arm (LFI; tumor bed and elective lymph node region) and small-field irradiation arm (SFI; tumor bed only). The primary endpoint was whether the disease-free survival (DFS) of SFI was not inferior to LFI. The secondary endpoint was to evaluate the rationality of the radiation target volume by analyzing failure patterns. One hundred twenty-one patients (64 patients for LFI and 57 patients for SFI, respectively) were eligible in this mid-time analysis. The 1- and 3-year DFS was 79.9%, 46.2% for LFI and 67.6%, 44.3% for SFI, respectively (P = 0.414). The locoregional recurrence-free survival (LRFS) of LFI was significantly better than that of SFI (P = 0.003). However, there were no significant differences in the distant metastasis-free survival and overall survival between the two arms (P = 0.332, P = 0.405, respectively). The failure patterns of the two arms were significantly different (P = 0.002). For pT3-4N0-3M0 ESCC patients, postoperative radiotherapy with SFI showed a similar survival outcome to LFI. However, the LRFS of patients with SFI was worse than that of patients with LFI.