Proximal margin and oncologic outcomes in gastric cancer: a contemporary multi-institutional study

This study aimed to evaluate the association of proximal margin (PM) status and length with oncologic outcomes following curative gastrectomy for gastric and gastroesophageal junction adenocarcinomas (GA and GEJA) using a contemporary Western multi-institutional cohort.

Patients who underwent curative-intent resection for GA and Siewert III GEJA from 2016 to 2020 at two U.S. institutions were included. Outcomes were compared between patients with positive and negative PMs. Margin length was analyzed continuously in millimeters using multivariable Cox proportional hazards models among all patients with negative PMs and separately among those with p/ypN0-N1 disease. The primary outcomes were recurrence-free survival (RFS) and overall survival (OS).

Among 412 patients, 54.9% received neoadjuvant chemotherapy, and 80.1% underwent minimally invasive surgery. Overall, 399 patients (96.8%) had negative PMs and 13 (3.2%) had positive PMs. Positive PMs were associated with larger tumors, advanced p/ypT and p/ypN stage, and perineural invasion. Among 343 patients with negative PMs and available margin measurements, PM length was not associated with RFS or OS in either the entire cohort or the p/ypN0-N1 subgroup (n=232). Pathologic TNM stage and age were independently associated with both RFS and OS in multivariable analyses.

In this contemporary Western multi-institutional cohort, increasing negative PM length was not associated with improved oncologic outcomes, including among patients with p/ypN0-N1 disease. Positive PMs were uncommon and occurred predominantly in patients with advanced disease.