Of 737 consecutive patients undergoing (sub)total gastrectomy for gastric or GEJ adenocarcinoma, 679 cases with curative intent surgery between 05/1996 and 03/2019 were included. Patients were categorized into: i) R0 without further resection (direct R0), ii) R0 after positive IOC and extension of resection (converted R0) and iii) R1.

This retrospective cohort study was performed at our tertiary referral center at the University Hospital of Cologne, Germany. Since 1st May 1996 medical charts of patients who undergo surgery for gastric or GEJ adenocarcinomas are collected in a department internal database for research analyses (Chairman since 05/2016 CJ Bruns, from 5/1996-4/2016 AH Hölscher).

In this study, patients undergoing curative surgery between 1st May 1996 and 31st March 2019 with (sub)total gastrectomy for gastric or GEJ adenocarcinoma were included. Palliative resections and resections with transthoracic esophagectomy and gastric pull-up were excluded.

Demographics, perioperative treatment, survival and clinicopathologic data were obtained. Medical records were reviewed and complications were categorized according to Clavien-Dindo classification.

Depending on IOCs, extended resection and final pathology report a treatment flow-chart was created (Figure 1): Patients were grouped on a) IOC received (yes/no), b) IOC positive (yes/no), c) extended resection (yes/no), d) second IOC (IOC2; yes/no), e) IOC2 positive (yes/no) and final pathology results (R0/R1). The decision to perform IOC and to carry out extended resection in case of positive IOC was at the discretion of the treating surgeon. Patients were then categorized into 3 subgroups according to final R status: R0 after extended resection (i.e. converted R0), R0 without extended resection (i.e. direct R0) and R1.

Inclusion Criteria:

• older than 18 years
• tumor resection via total gastrectomy and subtotal esophagectomy

Exclusion Criteria:

• no additional other solid or hematological neoplasias in the medical history
• pregnancy
• surgical procedures in palliative intention

This retrospective cohort study was performed at our tertiary referral center at the University Hospital of Cologne, Germany. Since 1st May 1996 medical charts of patients who undergo surgery for gastric or GEJ adenocarcinomas are collected in a department internal database for research analyses (Chairman since 05/2016 CJ Bruns, from 5/1996-4/2016 AH Hölscher).

In this study, patients undergoing curative surgery between 1st May 1996 and 31st March 2019 with (sub)total gastrectomy for gastric or GEJ adenocarcinoma were included.

Data is available by the responsible PI on reasonable request