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

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

Philip H. Pucher1#, Sivesh K. Kamarajah2#, Pradeep Bhandari1, Natalie Blencowe3, Tom Crosby4, Richard P. T. Evans2, Ewen A. Griffiths2,5, Sheraz R. Markar6, Nigel Trudgill2, Timothy J. Underwood7, James A. Gossage8; the CONGRESS collaborative

1Department of General Surgery, Queen Alexandra Hospital, Portsmouth Hospitals University NHS Trust, Portsmouth, UK; 2Department of Upper GI Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK; 3Department of Surgery, University of Bristol, Bristol, UK; 4Department of Oncology, Velindre University NHS Trust, Cardiff, UK; 5Institute of Immunology and Immunotherapy, University of Birmingham, BirminghamUK; 6Department of Surgery, Oxford University NHS Foundation Trust, Oxford, UK; 7Department of Surgery, University Hospitals Southampton NHS Foundation Trust, Southampton, UK; 8Department of Surgery, Guy’s and St Thomas’ Hospital NHS Foundation Trust, London, UK

Contributions: (I) Conception and design: All authors; (II) Administrative support: None; (III) Provision of study materials or patients: None; (IV) Collection and assembly of data: None; (V) Data analysis and interpretation: None; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

#These authors contributed equally to this work as co-first authors.

Correspondence to: Philip H. Pucher, MD, PhD. Department of General Surgery, Queen Alexandra Hospital, Portsmouth Hospitals University NHS Trust, Southwick Hill Road, Portsmouth PO6 3LY, UK. Email: philip.pucher@porthosp.nhs.uk.

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.

Keywords: Oesophagectomy; gastrectomy; early cancers; survival; outcome

Received: 01 February 2024; Accepted: 28 June 2024; Published online: 26 August 2024.

doi: 10.21037/ales-24-8

Introduction

The management of early oesophagogastric (OG) cancer is often considered the subject of controversy. Radical surgery (i.e., oesophagectomy or gastrectomy), historically the primary treatment strategy, is associated with substantial risk of morbidity, mortality, and is associated with significant reductions in long-term quality of life and functional status (1,2). Advances in endoscopic resection (ER) have meant that organ-preserving therapy is increasingly advocated for as an alternative treatment for early (Tis, T1), node-negative (N0) disease.

Most national guidelines including those of the USA, UK, Europe, and Japan currently recommend ER for early cancer not crossing the muscularis mucosae (T1a). The primary basis of treatment includes accurate clinical staging demonstrating node-negative localised disease and a low-grade tumour, with tumour size small enough to allow for complete resection with negative margins (3). With increasing depth of invasion comes an increased risk of lymph node involvement. Rates of occult nodal involvement in submucosal (T1b) cancer are generally quoted at between 4–16%, though some studies have reported rates as high as 50% for T1b cancers with higher risk features (4,5).

Owing to the risk of occult nodal disease, current guidelines generally advocate a more conservative approach—i.e., surgical resection—should be offered for T1bN0 disease. However, this simplistic approach to offer ER to T1a, and surgery to T1b disease overlooks numerous other prognostic factors other than depth of invasion known to be associated with risk of nodal metastasis, including presence of lymphovascular invasion, and grade of differentiation. Often patients undergoing radical oesophagectomy after R0 ER of T1b disease will have no residual detectable cancer. Current evidence used to support current guidelines are limited by institutional cohorts with small sample sizes, owing to the relative rarity of early OG cancer (6-9). Large administrative databases lack the granularity of data to conduct in-depth relevant analyses. Until better risk stratification based upon large granular datasets can identify those patients in which an organ preserving strategy is safe, the majority of patients risk overtreatment with surgical resection, and may suffer the sequelae of surgery unnecessarily.

CONGRESS (endosCopic resectiON, esophaGectomy or gastrectomy foR Early oeSophagogastric cancerS) aims to increase our understanding of the variability of international practice in patients with early stage OG cancers and characterise the impact of disease characteristics and treatment strategies on long-term survival.

Methods

A UK-based international audit will be delivered via the CONGRESS collaborative. A team of 2 to 4 surgical trainees or consultants from each centre will retrospectively collect data for patients diagnosed from January 2015 until December 2022, inclusive. All audit teams will be supervised by a named consultant from each centre. Intended study closure date including follow up is July 2023.

Treatments will be audited against existing international treatment guidelines (see Table 1), which agree that T1a tumours should be preferentially managed with ER, whilst T1b should be considered for surgical resection.

Table 1

Selected national guidelines for management of early oesophago-gastric cancer

Organisation, country/region Year Recommendation
National Comprehensive Cancer Network, USA (10) 2019 T1a: endoscopic resection or surgery
T1b: consider surgery
National Institute for Health and Care Excellence, UK (11) 2018 Oesophageal T1a: endoscopic resection
Oesophageal T1b: surgery (or definitive chemoradiation for squamous cell cancer)
Japanese Gastric Cancer Association, Japan (12) 2017 Gastric T1a: endoscopic resection
Gastric T1b: surgery (consider D1/D1+ lymphadenectomy)
Japan Esophageal Society, Japan (13) 2022 Oesophageal T1a: endoscopic resection (unless involving ≥3/4 of circumference due to stenosis risk). Consider surgery for T1a involving muscularis mucosae
Oesophageal T1b: surgical resection
European Society for Medical Oncology, Europe (14,15) 2016 T1a: endoscopic resection
T1b: surgery

Study aims

The primary aim of the audit is to assess compliance of management of early OG cancer for clinically staged T1a and T1b N0, or pathologically staged in case of ER, in an international cohort.

Secondary aims are:

  • To characterise differences in long-term survival between radical surgery and organ preserving treatment for both T1a and T1b N0 OG cancers.
  • To assess the impact of pre-operative staging modalities upon differences between clinical and pathological disease stage.

Centre eligibility

This study is open to all international centres offering treatment with curative intent for oesophageal and gastric cancer. This may include endoscopic, surgical, and oncological therapy. The study will be conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study will be approved by each contributing centre’s individual institutional review committees. As a retrospective study, the expectation of individual patient consent has been waived. In keeping with previous well-established methodology for multi-centre retrospective audits of clinical practice (16), 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.

Patient eligibility

Inclusion criteria:

  • Age: adult, 18 years or above.
  • Diagnosis: T1a or T1b N0 M0 cancer of the oesophagus, oesophago-gastric junction, or stomach. All histological subtypes will be included.

Exclusion criteria:

  • Patients receiving palliative or no treatment.

Patient identification

Patients will be identified via local multidisciplinary team (tumour board) meeting databases, and via coordination with local leads for OG cancer resections and ER. Coordination with upper gastrointestinal cancer nurses and procedural scheduling systems will enable screening of any patients missed.

Data collection

CONGRESS will measure current practice in the management of early OG cancer. Anonymised data will be collected on audit standards, and confounding factors in order to allow risk-adjusted analyses. These factors include centre-level (i.e., facility type, centre resources and case volume), patient-level [i.e., age, sex, race, year of diagnosis, Charlson comorbidity index scores, body mass index, American Society of Anaesthesiologists (ASA) grade, smoking status] and tumour-level (i.e., pathological stage, histological characteristics, margins, lymphovascular invasion) factors.

Recorded outcomes will include survival, disease recurrence, planned and delivered treatment, and surveillance practices.

A full list of data fields is presented in Appendix 1.

Additionally, a unit survey will accompany the audit, which will capture centre-level data on specialists involved in early OG cancer care, local practices, resources, and case volume, factors for which outcomes will be further adjusted.

Data governance

All CONGRESS data will be submitted and securely stored online via the Research Electronic Data Capture (REDCap) online programme (17). The programme allows contributors to enter data in a secure and anonymised fashion. Collaborators are given secure login details, allowing secure data storage.

Quality assurance

  • Design: this protocol has been written and reviewed by an international multidisciplinary steering committee including surgeons, gastroenterologists, and oncologists.
  • Study pilot: study methodology, patient identification, and data entry were trialled within the steering committee members’ centres with iterative amendments to the database to improve clarity, data field entry flow, and ease of use prior to opening to general recruitment.
  • Data completeness: following data collection, only data sets with >95% data completeness will be accepted for pooled national analysis. Any data collection periods with >5% missing data points will be excluded from the study; collaborators will be withdrawn for the list of published collaborators and data redacted if excess missingness is detected.
  • Validation: this methodology for trainee-driven audit has been widely validated across multiple datasets and has been shown to demonstrate high levels of case ascertainment (typically greater than 90% to 95%) and data accuracy (greater than 96% to 98%) (18,19).

Authorship

In accordance with National Research Collaborative (NRC) guidelines (20), all research collaborators will be credited.

Statistical analysis

The report of the audit will be prepared in accordance with the guidelines as set by the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement for observational studies and STROCSS (Strengthening the Reporting of Cohort Studies in Surgery) (21). Data will be collated, and missing data for predictor values replaced using multiple imputation method (five imputed datasets); all predictor and outcome variables will be used. Separately grouped analyses for the main histological subtypes of adenocarcinoma and squamous cell carcinoma will be performed. Multivariable logistic regression models will be used to assess impact of covariates on the overall and disease-free survival.

Discussion

The improvement of early identification and treatment of early OG cancer has lagged behind the numerous advances seen in oncological and surgical therapies for advanced disease (22,23). In the absence of endoscopic screening frameworks in Western practice, programmes to develop less invasive and cost-effective diagnostics continue (24-27). However, there remains significant equipoise over the true risk of local and metastatic progression for early disease, as well as its optimal management. Currently available data is limited largely to small datasets, a result of the relatively rare presentation of T1a and T1b disease in Western centres. This paper presents the protocol for a national audit which will seek to document the spectrum of treatment approach for early OG cancers, assembling a large multicentre dataset with particular focus on identifying the best approach for long-term patient survival. It is anticipated that the present study will use data from this cohort study to develop further ideas for further interventional studies in the future to improve outcomes in these unique subsets of patients.

Previously published data, included large administrative datasets from the US National Cancer Database demonstrated conflicting evidence on the benefit of curative surgery, compared to ER, for T1 OG cancer (9,28,29). In a recent study, representing perhaps one of the largest datasets on T1 disease, rates of node-positive disease for cT1a and cT1b cancers were 4% and 15%, respectively (29), highlighting the potential overtreatment which radical surgery make represent in these groups. Previous other literature on the management of cT1 esophageal cancer, especially cT1b, have been limited by very small sample sizes, precluding the drawing of valid or generalizable conclusions (30-34). A 2020 Cochrane review of endoscopic versus surgical treatment for early oesophageal cancer failed to identify even a single trial suitable for inclusion (35).

Historically, esophagectomy and gastrectomy has been regarded as the standard of care for early stage OG cancer (36) owing to good long-term survival. This benefit was seen despite a greater upfront risk of 90-day mortality of up to 7% seen in various reports from the United Kingdom (37), Sweden (38), Finland (39) and United States of America (40), although modern mortality rate is widely reported as <3% internationally in high volume centers (41). The risk of overtreatment and associated morbidity or mortality with surgery, versus the increasing use of ER and risk of missed occult nodal disease in early cancer highlights the need for accurate data to enable clinicians to appropriately counsel patients (42,43). It also underscores the critical need to understand the potential for inaccuracies within OG cancer staging, which severely limit current clinical practice, as clearly demonstrated in studies which routinely report a subset of patients staged cT1aN0 having positive lymph nodes after oesophagectomy.

Within ER, various techniques may affect outcome as well. ER via endoscopic mucosal resection (EMR) was previously reported to be a risk factor for postoperative local recurrence (44), whereas en-bloc resection is desirable for early cancers. Some evidence appears to suggest that endoscopic submucosal dissection (ESD) may be superior to EMR in terms of achieving en-bloc resection (44,45). Previous studies have not delineated impact of patients undergoing EMR vs. ESD, limiting the analysis of the long-term outcomes of either technique. Furthermore, there is a known relationship between volume and outcome for ER (46).

CONGRESS aims to address many of the limitations of existing publications, controlling for key factors and treatment options and achieving a large sample size through international, multicentric data recruitment. Its strengths include protocolised data collection and a planned capture of international practice from OG units across high, middle and low volume centres. This will allow the representation of true real-life practice and outcomes, rather than just of a few isolated high volume or academic centres. Potential limitations predominantly include those associated with voluntary retrospective data entry; prior similar study frameworks however have achieved excellent data completion and by setting minimum data completeness criteria for inclusion in the study we believe missing data will be limited.

Acknowledgments

This protocol was presented at the British Association for Surgical Oncology (BASO), London, UK, 2023.

Funding: None.

Footnote

Peer Review File: Available at https://ales.amegroups.com/article/view/10.21037/ales-24-8/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://ales.amegroups.com/article/view/10.21037/ales-24-8/coif). P.H.P. serves as an unpaid editorial board member of Annals of Laparoscopic and Endoscopic Surgery from February 2024 to January 2026. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study will be conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study will be approved by each contributing centre’s individual institutional review committees. As a retrospective study, the expectation of individual patient consent has been waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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doi: 10.21037/ales-24-8
Cite this article as: Pucher PH, Kamarajah SK, Bhandari P, Blencowe N, Crosby T, Evans RPT, Griffiths EA, Markar SR, Trudgill N, Underwood TJ, Gossage JA; the CONGRESS collaborative. Study protocol for a multicentre international collaborative cohort study on the management and outcomes for T1 oesophagogastric cancer (CONGRESS). Ann Laparosc Endosc Surg 2025;10:9.

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