The goal of the study is to understand whether blood levels of hormones produced or metabolized in the stomach reflect the health of the stomach lining.

Specifically the study will determine whether the concentration of ghrelin, gastrin, pepsinogens and vitamin B12 reflect the condition of the stomach lining. Hormone concentrations for people with normal/mild gastritis will be compared to people with long-term inflammation of the stomach (chronic atrophic gastritis), and people with pre-cancerous cellular changes (intestinal metaplasia).

Previously published promising data show that blood levels of ghrelin, gastrin, vitamin B12 and pepsinogen are each associated with risk of developing stomach cancer. These studies used blood bank samples and looked at risk of cancer many decades later. This study was designed to explore whether these markers could be useful in a clinical setting for early detection of stomach cancer.

The study will recruit at 3 sites over 1 year identifying patients with chronic atrophic gastritis and intestinal metaplasia and those with mild gastritis.

Only the patient data which is absolutely necessary for analysis will be collected, to include basic demographics, relevant medical history and medications. These data will be used to analytically account for alternative explanations for variation in blood measurements of ghrelin, gastrin, pepsinogen and vitamin B12.

A one-time venous blood sample will be collected to enable measurement of the markers of interest.

Inclusion Criteria:

1. Adult patients (18-80 years old) attending upper gastrointestinal endoscopy.
2. Patients able to read and comprehend English.
3. Patients willing and able to provide informed consent.
4. Patients willing and able to provide a venous blood sample.

Exclusion Criteria:

1. Any individual diagnosed with gastric cancer, or with a history of gastric cancer, prior gastrectomy or bariatric surgery.
2. Any individual with a chronic inflammatory condition of the gastrointestinal tract (Crohn's disease or ulcerative colitis).
3. Once enrolment ceiling is reached for each group, enrolment will close for that group. The study will continue until all groups are complete.

Patients scheduled for endoscopy within the endoscopy service at participating sites will be invited to participate in the study and provide a blood sample.