Chronic atrophic gastritis (CAG) — histologically confirmed loss of oxyntic and/or antral...

Deterministic view of the source YAML entity. Clinical authority remains with the cited source IDs and reviewer sign-off state.

ID	`RF-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION`
Type	Red flag
Status	reviewed 2026-05-18 \| pending_clinical_signoff
Diseases	`DIS-GASTRIC` `DIS-GI-NET`
Sources	`SRC-NCCN-BCELL-2025` `SRC-NCCN-GASTRIC-2025` `SRC-NCCN-NET-2025`

Red Flag Origin

Definition	Chronic atrophic gastritis (CAG) — histologically confirmed loss of oxyntic and/or antral gastric glands with replacement by intestinal metaplasia and/or pyloric metaplasia, most commonly secondary to autoimmune mechanism (anti-parietal and anti-intrinsic-factor antibodies, B12 deficiency, achlorhydria, elevated gastrin) or long-standing H. pylori infection. Established precursor lesion to gastric adenocarcinoma (intestinal type, ~5-10x lifetime relative risk; absolute risk ~1-2%/year for OLGA III/IV stages) and a potent risk factor for type 1 gastric neuroendocrine tumors arising from ECL-cell hyperplasia driven by chronic hypergastrinemia. No current gastric malignancy diagnosis. Endoscopic surveillance with topographic biopsies (updated Sydney protocol) per OLGA/OLGIM stage reduces gastric cancer mortality in high-risk subgroups. Prevention-persona RedFlag (§20 ratification 2026-05-1...
Clinical direction	investigate
Category	other

Trigger Logic

{
  "any_of": [
    {
      "finding": "chronic_atrophic_gastritis_histology_confirmed",
      "value": true
    },
    {
      "finding": "autoimmune_metaplastic_atrophic_gastritis",
      "value": true
    },
    {
      "finding": "olga_stage_3_or_4",
      "value": true
    },
    {
      "finding": "olgim_stage_3_or_4",
      "value": true
    }
  ],
  "type": "lab_value"
}

Notes

v0.3 chronic-condition prevention pilot — chronic atrophic gastritis (CAG). Prevention-persona RedFlag (CHARTER §3 amended 2026-05-18 Path A, HCP-mediated). Fires when patient profile shows histologically confirmed atrophic gastritis (autoimmune or post-H. pylori) AND no confirmed gastric malignancy. Engine routes to PreventionPlan with 2 tracks: EGD q3-5y with Sydney-protocol surveillance biopsies (IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-SURVEILLANCE) as standard; symptom-driven observation with B12 + iron monitoring only (IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-OBSERVATION) as alternative. Evidence base: - **Gastric cancer risk by OLGA/OLGIM stage:** Rugge et al. Gut 2018 (12-year prospective cohort): OLGA stage III/IV — 12-year gastric cancer incidence ~10-15%; OLGA stage 0-II — <1%. OLGIM (intestinal-metaplasia-specific) staging predicts similarly. - **MAPS II European Guideline (Pimentel-Nunes et al. Endoscopy 2019):** EGD with Sydney biopsies (2 antrum + 2 corpus + incisura) at diagnosis; q3y surveillance for advanced atrophy/IM (OLGA III/IV or OLGIM III/IV); q1y for IM with dysplasia or family history of gastric cancer. Optical-enhanced imaging (NBI, BLI) preferred wher...

Used By

Indications

IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-OBSERVATION - IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-OBSERVATION
IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-SURVEILLANCE - IND-CHRONIC-ATROPHIC-GASTRITIS-PREVENTION-SURVEILLANCE