Incidence of lymph node metastases in pT1 chemo- and radiotherapy-naïve esophageal and gastric cancer in the Nordic countries: a retrospective multinational cohort analysis.

Although endoscopic resection is reported to be safe for early-stage esophagogastric cancer, uncertainty remains regarding oncological efficacy, particularly for submucosal lesions. The aim of this study was to assess the frequency of lymph node metastasis (LNM) and survival in patients operated for chemo- and radiotherapy-naïve pT1 esophagogastric cancer. Patients who underwent surgical resection for esophageal or gastric pT1 adenocarcinoma or squamous cell carcinoma without neoadjuvant oncologic treatment were included. Data were retrospectively extracted from registries in Denmark (2013-2021), Norway (2007-2024), Sweden (2012-2022), and Finland (2000-2016). The primary outcome was the frequency of LNM in resected specimens from patients operated for pT1 esophagogastric cancer. Secondary outcomes included: 5-year overall survival, number of lymph nodes harvested, and risk factors associated with LNM and mortality. 1647 patients with pT1 tumors were identified, of whom 949 (58%) did not receive neoadjuvant treatment; 413 (43%) had esophagectomy and 536 (56%) gastrectomy. 145 (15%) patients had LNM identified in the resected specimens for esophagectomies, the LNM rate was 3% for pT1a and 20% for pT1b, and for gastrectomies, 7% for pT1a and 21% for pT1b. The median follow-up was 62 months (interquartile range: 33-102) and 5-year overall survival was 81% for patients with pT1a tumors and 65% for those with pT1b tumors. Among patients with pT1b, the overall survival was 69% without LNM and 51% with LNM. Depth of tumor invasion was associated with risk of LNM. A high proportion of patients had LNM after resection for chemo- and radiotherapy-naïve pT1 esophagogastric cancer.