Background Ensuring a pathologically negative distal margin (DM) and preserving a larger remnant stomach is important for proximal gastrectomy (PG) in patients with esophagogastric junction (EGJ) cancer. However, the minimum DM length for ensuring negative margins has not been identified. Methods We enrolled patients undergoing PG or total gastrectomy for EGJ cancer. A parameter Delta DM, representing the pathological extension distally beyond the gross tumor boundary, was evaluated. The maximum Delta DM, which indicates the minimum length ensuring a pathologically negative DM, was determined in all patients. Subgroup analyses were performed according to factors associated with Delta DM > 10 mm. The possible incidences of pathologically positive DM based on gross DM length were also calculated. Results Among 253 eligible patients, the maximum Delta DM was 55 mm. Growth and pathological types were significantly associated with Delta DM > 10 mm. In subgroup analyses, the maximum Delta DM was 30/20/55 mm for the superficial/expansive/infiltrative growth types, and 55/40 mm for the differentiated/undifferentiated types. In the infiltrative growth type alone, the maximum Delta DM remained 55/40 mm for the differentiated/undifferentiated types. However, even if the gross DM length was reduced to 30 mm, the possible incidence of pathologically positive DM only increased to 2.6% in the infiltrative differentiated type. Conclusion We recommend a minimum DM length of 30/20/55 mm for the superficial/expansive/ infiltrative growth types. Specifically in the infiltrative growth type, we alternatively recommend 30/40 mm for the differentiated/undifferentiated types, with a mandatory intraoperative frozen section analysis. Mini-abstract This study proposes a distal margin length for safe resection of esophagogastric junction cancer, ensuring pathologically negative margins while preserving a larger remnant stomach, based on growth and pathological types.
