Impact Of Adjuvant Therapy In Patients With A Microscopically Positive Margin After Resection For Gastroesophageal Cancer.

164Background: A microscopically positive (R1) resection margin following resection for gastroesophageal (GE) cancer has been documented to be a poor prognostic factor. The optimal strategy and impact of different modalities of adjuvant treatment for an R1 resection margin remain unclear. Methods: A retrospective analysis was performed for patients (pts) with GE cancer treated at the Princess Margaret Cancer Centre from 2006-2016. Electronic medical records of all pts with an R1 resection margin were reviewed. Kaplan-Meier and Cox proportional hazards methods were used to analyze recurrence free survival (RFS) and overall survival (OS) with stage and neoadjuvant treatment as covariates in the multivariate analysis. Results: We identified 78 GE cancer pts with an R1 resection. 11% had neoadjuvant chemotherapy, 14% chemoradiation (CRT), 75% surgery alone. 28% had involvement of the proximal margin, 13% distal, 56% radial, 3% had multiple positive margins. By the American Joint Committee on Cancer 7th editio...