Patients

A retrospective analysis was performed for patients with gastric and esophageal adenocarcinoma treated at the Princess Margaret Cancer Centre (PMCC) from 2006–2016. Patients included had curative intent surgical resection either within the University Health Network or at an outside institution. Patients referred postoperatively from an outside institution were reviewed by a multidisciplinary team consisting of surgical oncologists, medical oncologists, radiation oncologists, radiologists and pathologists whenever possible. This study was approved by the University Health Network Research Ethics Board. Electronic medical records of all patients with an R1 resection margin were reviewed. Data was collected by trained abstractors and all extracted data was verified by a second investigator. The pathological stage was classified using the American Joint Committee on Cancer (AJCC) 7th edition TNM staging system. The presence of tumor within 1mm of the surgical margin was used to define a R1 resection, as stipulated by the Royal College of Pathologists’ criteria.