Data will be extracted from routinely collected hospital databases.

Electronic medical records; Endoscopy and pathology databases; Surgical and hospitalization records; Oncology treatment databases; Imaging and diagnostic services; Institutional mortality records.

Inclusion Criteria:

Cohort A:

• Eligible participants were adults aged 50 to 75 years or older who had been referred for colonoscopy as part of the national colorectal cancer screening programme, following a positive FIT. To be included, individuals also needed to provide informed consent and agree to undergo an EGD endoscopy for the screening of potential upper gastrointestinal precancerous conditions or lesions.

Cohort B:

• Patients with gastric adenocarcinoma, diagnosed and treated at Unidade Local de Saúde do Alto Alentejo between 2015 and 2020.

Exclusion Criteria:

Cohort A:

• Exclusion criteria included a prior diagnosis of gastric cancer, as well as any condition that would prevent the safe performance of the EGD or the collection of gastric mucosal biopsies. Previous EGD was not listed as an exclusion criterion.

Cohort B:

• Other types of gastric tumors.
• Gastric involvement from metastatic disease of another primary tumor.

Cohort A - Opportunistic screening cohort A cohort of FIT-positive individuals undergoing colonoscopy for colorectal cancer screening, with the addition of opportunistic EGD during the same procedure.

Cohort B - Gastric cancer cohort A retrospective cohort including all patients diagnosed with gastric adenocarcinoma in the institution over a 10-year period.

Publication on index journal

2015 to 2020