300. endoscopic follow-up of radically resected submucosal esophageal adenocarcinoma: preliminary results of an ongoing prospective, international, multicenter cohort registry (prefer trial)

Abstract Introduction Current guidelines advise esophagectomy for submucosal esophageal adenocarcinoma (T1b EAC). Data from retrospective studies suggest that endoscopic follow-up (FU) may be a valid alternative in patients without signs of lymph node metastases (LNM) at baseline. Our aim is to evaluate the safety of a watchful waiting strategy with regular endoscopic FU as an alternative in patients treated endoscopically for T1b EAC (NCT03222635). Methods This study, conducted at 19 hospitals in Europe and Australia, aims to include 141 patients with 5-year FU. After endoscopic resection of T1b EAC (R0), patients are re-staged with endoscopic ultrasound (EUS) and CT/PET. Patients (N0M0) undergo strict endoscopic FU with gastroscopy and EUS. CT/PET is repeated after 1 year. The cohort is divided into ‘high-risk’ (submucosal invasion ≥500um, a/o poorly/undifferentiated tumor (G3–4), a/o lymphovascular invasion (LVI+)) and ‘low-risk’ (risk features absent). Outcome parameters are 5-year disease specific survival, overall survival, rates of LNM and local recurrence. Results 134 patients (112 men, median age 69) underwent median FU of 22 (IQR 11–35) months: 87 high-risk and 47 low-risk. 6 patients (4% [95%CI 0.2–8.8]) were diagnosed with LNM after median FU of 8 (IQR 5–16) months. 2/6 underwent neoadjuvant chemo(radio)therapy with esophagectomy (ypT0N1M0, ypT0N0M0), 1/6 underwent esophagectomy only (pT0N2M0), 3/6 underwent selective surgical LN resection. 7 patients (5% [95%CI 0.8–9.6] were diagnosed with an intra-luminal tumor recurrence not eligible for endoscopic re-treatment after median FU of 7 (IQR 6–15) months. 2/7 underwent esophagectomy (pT1bN0M0, pTisN0M0), 1/7 had neoadjuvant chemoradiotherapy and esophagectomy (ypT1aN0M0), 3/7 underwent (chemo)radiotherapy only, of which 1 patient eventually died as result of stenosing EAC, 1/7 refused additional treatment. No distant metastases were diagnosed. Five patients died of an EAC-unrelated cause. Five patients discontinued FU due to old age. Two patients were lost to FU. Conclusion The preliminary analysis from our ongoing prospective study suggest that in patients with radically removed high- or low-risk T1b EAC, without LNM at baseline, a strict endoscopic follow-up protocol is feasible and the window for curative therapy remains open for those patients who develop LNM (4%) or a local intra-luminal recurrence (5%) during FU. Most patients demonstrate uneventful FU.