Study protocol for a multicentre international collaborative cohort study on the management and outcomes for T1 oesophagogastric cancer (CONGRESS)

Background: Controversy remains surrounding the optimal management of patients with T1N0 early oesophagogastric (OG) cancer. Individual units often see low numbers of patients with very early stage disease; previous publications are limited to smaller institutional cohorts or less granular administrative databases. The endosCopic resectiON, esophaGectomy or gastrectomy foR Early oeSophagogastric cancerS (CONGRESS) collaborative aims to characterise the impact of different management strategies, including endoscopic resection (ER) and radical surgery, with detailed disease and outcome data, for early OG cancer in a large multi-centre cohort study. Methods: An international retrospective cohort study will be performed, including all patients diagnosed with T1N0 OG cancer from 2015 to 2022. Led by local and regional collaborators, centralised anonymised data capture will include all relevant diagnostic, demographic, treatment, and outcome data. Treatment will be compared to current guidelines. For T1a disease, ER may be carried out if clearly confined to the mucosa, well differentiated, ≤2 cm and non-ulcerated. For T1b disease, radical oesophagectomy or gastrectomy may be considered. Discussion: This will be a large-scale international audit to identify and summarise current practice relating to the diagnosis, treatment and outcomes for early OG cancers. It is anticipated that this will allow detailed risk stratification for disease and treatment strategies and will provide the basis for further prospective interventional studies. Trial Registration: In keeping with previous well-established methodology for multi-centre retrospective audits of clinical practice, this study will be approved by local audit committees, as such it does not meet criteria to be and has not been registered with any central registry. Each centre will be responsible for locally registering the audit and obtaining appropriate permissions from local institutional review committees.