The optimal length of the proximal resection margin in patients with proximal gastric adenocarcinoma: A multi-institutional study of the U.S. Gastric Cancer Collaborative.

108 Background: A 5cm margin is advocated for distal gastric cancers. The optimal length of the proximal resection margin (PM) for proximal (GEJ Siewert II and III, cardia, and fundus) gastric adenocarcinoma (GAC) is not established. Methods: Patients who underwent curative intent abdominal-approach resection for proximal GAC from 2000-2012 at 7 academic US institutions were included. Patients with positive distal margins were excluded. PM length was analyzed by 0.5cm increments and was also dichotomized at the mean and median value. Primary endpoints were local recurrence (LR), recurrence-free survival (RFS) and overall survival (OS). Results: Out of 965 patients, 211 had proximal GAC, and 162 had data available on PM length. 151 patients had negative microscopic margins with a mean value of 2.6cm and a median of 1.7cm (range 0.1-15cm). When PM length was sequentially dichotomized and analyzed at 0.5cm increments (0.5-6.5cm), a greater margin distance for each analysis was not associated with LR, RFS, or OS. Similarly, a PM distance greater than the mean or median value was not associated with LR, RFS, or OS. 11 patients had a positive PM (R1), which was associated with higher N-stage (N3: 73% vs 26%; p=0.007) and increased LR (HR6.1; p=0.009). When accounting for other adverse prognostic factors (grade, lymphovascular invasion, tumor size, T-stage, and N-stage), a positive PM was not independently associated with LR. A positive PM was also not associated with decreased RFS or OS. Conclusions: For an abdominal-approach resection of proximal gastric adenocarcinoma, the length of the proximal margin is not associated with local recurrence, recurrence-free survival, or overall survival. A positive microscopic margin is associated with advanced N-stage but is not independently associated with recurrence or survival. When performing an abdominal-approach resection of proximal gastric adenocarcinoma, a grossly negative proximal margin is sufficient. Efforts to achieve a specific margin distance, especially if it necessitates an esophagectomy, should be abandoned.