Long-term outcomes after endoscopic resection of gastric adenocarcinoma of the fundic gland type and oxyntic gland adenoma: a retrospective cohort study

Gastric adenocarcinoma of the fundic gland type (GA-FG) and oxyntic gland adenoma (OGA) are recently recognized neoplasms arising from the oxyntic mucosa; however, their long-term clinical behavior after endoscopic treatment remains poorly defined. Here, we present one of the largest multicenter cohorts with extended follow-up to clarify their long-term outcomes. We retrospectively analyzed 72 patients who underwent endoscopic resection, with a mean clinical follow-up of 68 months. No disease-specific deaths were observed during follow-up. Among 66 patients with adequate endoscopic follow-up, the mean endoscopic follow-up period was 65 months. Remarkably, no local recurrence was observed, confirming durable local control after resection. Despite this excellent prognosis, metachronous lesions developed in 3 patients (4.5%) at distinct gastric sites, all of which were successfully treated endoscopically. These findings demonstrate that GA-FG/OGA exhibit indolent behavior with outstanding long-term outcomes following endoscopic resection. However, the occurrence of metachronous tumors suggests a field cancerization-like process in the oxyntic mucosa, underscoring the need for long-term surveillance.