Oesophagogastric cancer (cancer of the gullet and stomach) is the fifth most common cancer in England and Wales with 16,000 new cases diagnosed every year. Survival rates are poor with only 15% surviving beyond 5 years. There is also increasing research to understand the cancer biology and factors allowing cancers to progress. It is likely there is a relationship between the cancer-specific microbiome, cells related to inflammation, which promotes cancer progression. The BIORESOURCE 1 study has established a comprehensive resource of matched samples from patients with oesophageal and gastric cancer. This longitudinal study aims to obtain further matched biosamples in the follow-up period after cancer surgery to find biomarkers that may predict treatment response, recurrence and/or long term prognosis.

Inclusion Criteria:

• Aged 18-90 years at the time of initial recruitment
• Gastric/oesophageal adenocarcinoma cohort (biopsy proven adenocarcinoma) recruited into BIORESOURCE 1

Exclusion Criteria:

• Oesophageal squamous cell carcinoma
• Previous oesophageal and gastric resection
• History of another cancer within five years. If a new other cancer type is diagnosed within the sampling time frame, no further samples will be taken.
• Participants with co-morbidities preventing breath collection
• Unable or unwilling to provide informed written consent
• Pregnant women

Patients seen in a hospital (secondary or tertiary level care) setting