Nearly 10,000 people die each year in the United Kingdom from cancer of the lower gullet and stomach, known as known as oesophago- gastric adenocarcinoma (OGC). OGC is detected late as symptoms are non- specific and often mistaken for common problems such as heartburn. This translates to fewer than 2 in every 10 patients diagnosed with OGC living longer than 5 years.

The breath of people with OGC is enriched with volatile chemicals (VOCs) that indicate cancer. When measured in a breath test, it detects OAC 80 out of 100 times. Whilst encouraging, there is scope to improve the detection rate by giving patients a stimulant drink that amplifies the production of tumour specific VOCs only, to increase their detection in the breath test.

The goal of this observational study is to produce an enhanced second-generation breath test with superior ability to detect OGC through augmentation of breath. This will improve long term survival from cancer using an entirely non- invasive test.

All participants (cancer and control participants) will consume an oral stimulant drink (OSD) and provide breath samples pre and post consumption of the drink at set time points (maximum 2 hours after consumption of the drink).

The investigators will compare the breath VOCs from both groups, before and after consumption of the OSD to see if the OSD has a desired augmentation effect and can improve the accuracy of the OGC breath test.

With this second-generation breath test, participants with vague symptoms can undergo a quick, non- invasive test, have samples analysed in a safe and accurate manner and be subsequently stratified based on their risk of having OGC, leading to earlier disease detection and improved clinical outcomes.

Introduction: Early detection of oesophago- gastric adenocarcinoma (OGC) with improved diagnostics is essential to reduce the burden of this aggressive cancer. The breath of people with OAC is enriched with volatile organic compounds (VOC). A breath test based on these VOCs has an 80% sensitivity and 81% specificity of detecting OAC. The diagnostic accuracy may be further improved by using an exogenous stimulant that amplifies the production of OGC specific VOCs. This strategy is known as 'augmentation'. It is possible to compare intra- subject breath (pre and post stimulant) and use the fold increase in VOCs to detect cancer. This is the investigator's novel approach to improving breath test sensitivity and early OGC detection. The biology of the OGC VOCs must be first understood to selectively augment their production.

Background: The OGC lipidome is enriched with phospholipids that are vulnerable to degradation via lipid peroxidation, which is a principal mechanism for endogenous VOC production. Prokaryotic lipids in the OGC microbiome are also vulnerable to peroxidation. Putative drivers of lipid peroxidation are higher in tumour environment. This suggests OGC lipids and/ or prokaryotic lipids may be source compounds for diagnostic VOCs and this mechanism may be augmented.

Aim: to augment the production of OGC VOCs to improve the diagnostic performance of the breath test.

Proposal: 1) A lipidomics study of the onco- microbial lipidome using bespoke mass spectrometry with phenotyping of the corresponding VOCs will identify source lipids that generate diagnostic VOCs, 2) data driven stable isotope experiments to select an augmentation model based on the degradation kinetics of the source lipid in vivo and 3) translating the science to clinic with a study of the augmented breath test in participants with OGC.

Translation of the novel scientific data generated to clinic presents a real opportunity to improve clinical outcomes in people with OGC.

Inclusion Criteria:

• Participants should be over 18 years old and up to the maximal age of 90 years , AND:
• Have a confirmed histological diagnosis of oesophageal OR gastric adenocarcinoma at Imperial NHS Healthcare Trust, AND
• Will undergo am oesophagogastroscopy (OGD) as part of their routine clinical care, OR:
• Will undergo surgical resection of their oesophageal or gastric cancer as part of their routine clinical care OR
• Any patient with non- cancerous upper gastrointestinal (benign) problem who will have an OGD OR surgery as part of their routine clinical care at Imperial NHS Trust

Exclusion Criteria:

• Participant that lacks capacity or is unable to provide informed consent
• Any participant below 18 years of age or over 90 years of age
• Participants with allergies to any aspect of the metabolic drink
• Participants who have had previous OG surgical resection

Metabolomic and experimental data will be shared as participants will be given a unique identifier rendering the information anonymous. All other data collated will be stored in a central secure repository under an embargo and will be suitable for sharing following approval by the Chief Investigator.

New users can access a simple study policy and summarised data on the Imperial Clinical Research Network study website. Research data will also be discovered on the NIHR In-Vitro Diagnostic Co-operative website. Data will be disseminated through presentation at leading conferences that are accessible to subject specific and generalist audiences. Publication in high impact journals will allow global discovery of data to new users.

Decisions to supply research data to new users will be made by: Dr Anuja Mitra, Professor Griffin and Professor Hanna (PI).

3 years after the study has completed recruitment (December 2026). The information will be available for sharing for 2 years after that (until December 2028).

Decisions to supply research data to new users will be made by: Dr Anuja Mitra, Professor Griffin and Professor Hanna (PI).