Laparoscopic vs. open lower mediastinal lymphadenectomy for Siewert type II/III adenocarcinoma of esophagogastric junction: An exploratory, observational, prospective, IDEAL stage 2b cohort study (CLASS-10 study).

Objective: This study aims to verify the feasibility and efficacy of laparoscopic lower mediastinal lymphadenectomy for Siewert type II/III adenocarcinoma of esophagogastric junction (AEG).

Setting: An exploratory, observational, prospective, cohort study will be carried out under the Idea, Development, Exploration, Assessment and Long-term Follow-up (IDEAL) framework (stage 2b).

Participants: The study will recruit 1,036 patients with cases of locally advanced AEG (Siewert type II/III, clinical stage cT2-4aN0-3M0), and 518 will be assigned to either the laparoscopy group or the open group.

Interventions: Patients will receive lower mediastinal lymphadenectomy along with either total or proximal gastrectomy.

Primary and secondary outcome measures: The primary endpoint is the number of lower mediastinal lymph nodes retrieved, and the secondary endpoints are the surgical safety and prognosis, including intraoperative and postoperative lower-mediastinal-lymphadenectomy-related morbidity and mortality, rate of rehospitalization, R0 resection rate, 3-year local recurrence rate, and 3-year overall survival.

Conclusions: The study will provide data for the guidance and development of surgical treatment strategies for AEG.

Trial registration number: The study has been registered in ClinicalTrials.gov (No. NCT04443478).