European Implementation Study on Simultaneous Screening for Gastric and Colorectal Cancers

• Fecal sample acquisition for Helicobacter pylori stool antigen test (Diagnostic test): Participants will be offered to perform Helicobacter pylori (H. pylori) Stool antigen test (SAT) for H. pylori infection identification. SAT may be used after eradication therapy to confirm H. pylori eradication success instead of 13C Urea Breath Test.
• Upper endoscopy with biopsies (Diagnostic test): Upper endoscopy will be offered to participants with positive family history and/or alarm symptoms if such are identified (SAT and FIT negative individuals may not undergo questioning for the presence of alarm symptoms), provided a quality-assured endoscopic procedure has not been performed recently.
• Colonoscopy with biopsies after bowel cleansing (Diagnostic test): Colonoscopy will be offered to participants with positive FIT results, or positive family history, provided a quality-assured endoscopic procedure has not been performed recently; or such participants will be managed within national CRC screening programme.
• Helicobacter pylori eradication therapy (Drug): Helicobacter pylori eradication (antimicrobial) therapy offered to participants with Stool antigen test positive results. The recommended approach for first line treatment is bismuth quadruple therapy for 10-14 days, combined with a high-dose PPI BID. The recommended second line eradication medication: Levofloxacin-based quadruple/triple for 14 days plus high-dose PPI BID.
• Fecal sample acquisition for Fecal Immunochemical test (Diagnostic test): Participants will be offered Fecal Immunochemical test for colorectal cancer screening.
• Breath sample acquisition for 13C Urea Breath Test (Diagnostic test): 13C Urea Breath test will be offered to participants at least 4 weeks after Helicobacter pylori eradication therapy end for eradication success control.

Primary outcomes

• Percentage of invited individuals who return a Stool antigen test (SAT) sample. [Within 30 days after test kit distribution, according to site-specific procedures.]: Number of invited individuals who return a SAT sample divided by the number invited, multiplied by 100.
• Percentage of eligible individuals who receive a study invitation [During the study recruitment period, up to 12 months.]: Number of eligible individuals who receive a study invitation divided by the number of eligible individuals identified for invitation, multiplied by 100.
• Percentage of stool antigen test (SAT)-positive participants who start Helicobacter pylori Eradication Therapy [From positive SAT result through initiation of eradication therapy, up to 12 months]: Number of SAT-positive participants who start eradication therapy divided by the number of SAT-positive participants, multiplied by 100.
• Helicobacter pylori eradication rate [At least 4 weeks after completion of eradication therapy, up to 12 months]: Number of SAT-positive participants offered eradication therapy who have a negative post-treatment confirmatory test (stool antigen test or 13C-urea breath test), divided by the number of SAT-positive participants offered therapy, multiplied by 100.
• Participant-reported reasons for participation in or refusal of Helicobacter pylori testing [At the screening participation decision.]: Participant-reported reasons for participation in or refusal of Helicobacter pylori testing, summarized by response category.

Secondary outcomes

• Percentage of participants who take at least 90% of prescribed eradication therapy [From initiation through completion of eradication therapy (10-14 days)]: Number of participants who take at least 90% of prescribed doses, divided by the number who start therapy, multiplied by 100.
• Percentage of referred participants who undergo upper gastrointestinal endoscopy [Through study completion, an average of 1 year]: Number of participants referred for upper gastrointestinal endoscopy who undergo the procedure divided by the number of participants referred for upper gastrointestinal endoscopy, multiplied by 100.
• Percentage of participants meeting criteria for referral to upper gastrointestinal endoscopy [At initial screening assessment]: Number of participants meeting protocol-defined criteria for referral to upper gastrointestinal endoscopy divided by the number of participants assessed for the applicable referral criteria, multiplied by 100.
• Percentage of returned Stool antigen test (SAT) samples not valid for testing [Through study completion, an average of 1 year]: Number of returned SAT samples rejected as invalid divided by the total number returned, multiplied by 100.
• Reasons for invalid Stool Antigen Test (SAT) samples [Through study completion, an average of 1 year]: Reasons returned SAT samples are considered invalid for testing, including late return and inappropriate sample collection, summarized by reason category.
• Percentage of Fecal immunochemical test (FIT)-positive participants who undergo follow-up colonoscopy [Through study completion, an average of 1 year]: Number of FIT-positive participants who undergo colonoscopy divided by the number of FIT-positive participants, multiplied by 100.
• Colonoscopy findings among Fecal immunochemical test (FIT)-positive participants undergoing follow-up colonoscopy [Through study completion, an average of 1 year]: Colonoscopy findings among FIT-positive participants who undergo follow-up colonoscopy, summarized by finding category.
• Helicobacter pylori positivity by Stool antigen test (SAT) among participants [Through study completion, an average of 1 year]: Number of participants with a positive SAT divided by the number with a valid SAT result, multiplied by 100.
• Percentage of participants with a positive Fecal Immunochemical Test (FIT) [Through study completion, an average of 1 year]: Number of participants with a positive FIT result divided by the number of participants with a valid FIT result, multiplied by 100.
• Percentage of invited individuals who return a Fecal Immunochemical Test (FIT) sample [Through study completion, an average of 1 year]: Number of invited individuals who return a FIT sample divided by the number of invited individuals, multiplied by 100.
• Percentage of participants who complete post-treatment H. pylori eradication confirmation testing [At least 4 weeks after completion of eradication therapy, up to 12 months]: Number of participants who complete post-treatment confirmatory testing divided by the number of participants eligible for post-treatment confirmatory testing, multiplied by 100.
• Reasons for non-completion of H. pylori eradication therapy [During eradication therapy (10-14 days).]: Participant-reported reasons for completing less than 90% of the prescribed eradication therapy, including self-reported adverse effects and other factors contributing to discontinuation.
• Upper gastrointestinal endoscopic findings [Through study completion, an average of 1 year]: Endoscopic findings among participants who undergo upper gastrointestinal endoscopy, summarized by finding category.
• Upper gastrointestinal histological findings [Through study completion, an average of 1 year]: Histological findings among participants with biopsy specimens obtained during upper gastrointestinal endoscopy, summarized by finding category.

Sex: All, ages: 50 Years to any, accepts healthy volunteers

Inclusion Criteria:

* age 50 years and above (the actual recruitment age corresponds to the first CRC-screening age in each participating country/region);

Exclusion Criteria:

* personal history of gastric cancer;
* personal history of colorectal cancer;
* successfully screened via national colorectal cancer screening programme;
* inability or unwillingness to provide informed consent.

• Study Protocol and Statistical Analysis Plan (PDF, 2026-09-24)
• Informed Consent Form (PDF, 2026-07-18)

• Marcis Leja, Professor, Principal investigator, University of Latvia