The Role of Endoscopic Resection in Long-Term Results of Chemoradiotherapy for T1bN0M0 Thoracic Esophageal Squamous Cell Carcinoma.

PURPOSE/OBJECTIVE(S) An analysis of long-term treatment results of chemoradiotherapy (CRT) for T1bN0M0 thoracic esophageal squamous cell carcinoma (TESCC) at our institution suggested that the appropriate combination of endoscopic resection (ER) with CRT may lead to improved local control and organ-conserving survival (OCS). Here, we investigated the role of ER in the long-term outcomes of CRT for T1bN0M0 TESCC. MATERIALS/METHODS We retrospectively analyzed the cases of 91 patients with T1bN0M0 (UICC, 7th) TESCC treated with CRT from 2004 to 2017 at a single facility. There were 63 patients who were pathologically diagnosed with T1b based on ER results and then treated with additional CRT (ER+CRT group) and 28 patients who were diagnosed clinically as having T1b without ER and underwent definitive CRT (dCRT group). We determined the OCS and adverse events and compared the rates of local recurrence-free survival (LRFS) and overall survival (OS) between the two groups. RESULTS The median observation period was 61 months. The 5-year OS rate of the ER+CRT group was 78.0% (95% CI: 67.4-88.6) and that of the dCRT group was significantly lower at 63.5% (95% CI: 43.9-83.1) (P = 0.312). However, the 5-year LRFS rate of the ER+CRT group at 93.2% (95% CI: 85.6-100) was significantly higher than that of the dCRT group at 74.9% (95% CI: 56.9-92.9) (P < 0.001). Regarding the relapse pattern, intra-esophageal recurrence was the most common, observed in 11 patients (ER+CRT: 3, dCRT: 8), and salvage ER was performed in nine of the 11 patients. The 5-year OCS rate of all patients including who underwent salvage treatment was 72.0% (95% CI: 62.0-82.0). The most notable late adverse event (Grade 3 or higher) was pneumonitis in three patients. CONCLUSION The organ-conserving treatment for TESCC with submucosal invasion has been mainly CRT, but the problem of local recurrence after CRT (compared to esophagectomy) remains. Our long-term results suggest that ER improved the local control and enabled salvage treatment with a minimally invasive procedure. The combination of ER with CRT provides long-term survival that is comparable to that of esophagectomy, in addition to a high organ conservation rate.