The Correa Cascade: Gastric Carcinogenesis
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Direct answer
Pelayo Correa's cascade, proposed in 1975, models intestinal-type gastric adenocarcinoma as a multistep progression over decades: Helicobacter pylori-associated chronic non-atrophic gastritis → multifocal atrophic gastritis (beginning at the antral-corpus junction incisura) → intestinal metaplasia → dysplasia → invasive carcinoma. The inflammatory engine is CagA-positive H. pylori infection driving chronic oxidative and immunologic injury; the cascade stalls or slows when the infection is eradicated before metaplasia is established. Modern reporting quantifies where a patient sits on this ladder using the OLGA and OLGIM staging systems, which cross-tabulate the most severe atrophy (OLGA) or intestinal metaplasia (OLGIM) scores in antrum versus corpus biopsies into stages 0-IV, with stages III-IV identifying the high cancer-risk stomach that merits endoscopic surveillance.
What you must remember
- Sydney system biopsy protocol: two antral, one incisural, two corporal biopsies (five-site standard), graded 0-3+ for H. pylori density, neutrophils, mononuclear infiltrate, atrophy and intestinal metaplasia — the raw data OLGA feeds on.
- OLGA versus OLGIM: identical matrix logic; OLGIM scores only intestinal metaplasia and is more reproducible between pathologists, since atrophy is hard to separate from inflammation-lamina collapse.
- Stage arithmetic: antrum and corpus each contribute the highest atrophy/IM score; corpus-dominant stage III-IV (e.g., corpus IM score 3 with antrum 2) marks the highest gastric cancer risk group.
- Metaplasia typing: complete (type I, small-intestinal, absorptive cells with brush border) versus incomplete (types II-III, gastric mucin with sulphomucins in type III) — incomplete type III carries the higher progression risk.
- Pepsinogen method: pepsinogen I:II ratio below about 3 with raised gastrin-17 reflects corpus atrophy — the serum "biopsy" used in Japanese ABC screening triage.
- Two corpus-atrophy consequences: achlorhydria with hypergastrinaemia, and enterochromaffin-like cell hyperplasia → type 1 gastric neuroendocrine tumours (indolent, multiple).
- Intestinal versus diffuse gastric cancer: Correa's model applies to the intestinal type; diffuse signet-ring cancer (CDH1-related in the hereditary form) does not pass through metaplasia.
- Indian reality: H. pylori seroprevalence in Indian adults is high in most surveys, and non-cardia gastric cancer remains common — but routine OLGA/OLGIM reporting is still limited to larger centres, making the staging a useful differentiator in DM answers.
Working through a 48-year-old's gastric mapping biopsies
A 48-year-old with epigastric discomfort and a family history of gastric cancer undergoes biopsy mapping: two antrum, one incisura, two corpus. Histology shows H. pylori-positive chronic active gastritis with intestinal metaplasia score 2 in the antrum and incisura but score 0 in the corpus. The Sydney report is synthesised, then staged: OLGA stage II (antrum-predominant metaplasia), OLGIM stage II. Management follows the numbers: eradicate H. pylori (clarithromycin-based triple therapy where resistance is low, or bismuth quadruple therapy in high-resistance Indian settings), document eradication by urea breath test or stool antigen, and — because stage II is intermediate risk — individualise surveillance rather than enrol automatically.
Contrast a second patient whose mapping shows corpus-dominant atrophy with metaplasia score 3, anti-parietal cell antibodies positive and pepsinogen I:II ratio under 3: this is autoimmune metaplastic atrophic gastritis, OLGIM stage III-IV. Her pathway includes annual-to-biennial endoscopic surveillance for both adenocarcinoma and type 1 NETs, iron and B12 monitoring, and the recognition that the cancer risk of the autoimmune stomach equals that of the H. pylori atrophic stomach once the mucosa is fully metaplastic.
High-yield viva angles
Examiners probe three things. First, reversibility — honest answer: eradication reliably reverses gastritis and probably halts progression before metaplasia; established metaplasia rarely regresses, so surveillance rather than cure is the strategy. Second, why the incisura biopsy — atrophy begins at the antral-corpus transitional mucosa, the junctional zone where the cascade ignites, so skipping it under-stages the stomach. Third, the OLGA matrix itself: candidates must be able to recite that only the highest score per compartment enters the matrix and that stage III-IV requires severe atrophy in both compartments or severe corpus disease — the specific combination that predicts the "cancer stomach". A neat one-liner to close: Correa gave pathology the timeline, Sydney gave it the units, and OLGA converted the units into risk.
Frequently asked questions
What are the steps of the Correa cascade?
Chronic non-atrophic gastritis, multifocal atrophic gastritis, intestinal metaplasia, dysplasia, and finally intestinal-type adenocarcinoma — a decades-long H. pylori-driven progression.
How does OLGIM differ from OLGA?
OLGIM stages only intestinal metaplasia while OLGA stages atrophy; the matrix and stages 0-IV are shared, and OLGIM is more reproducible between observers.
Which type of intestinal metaplasia carries higher cancer risk?
Incomplete metaplasia, particularly type III with sulphomucin-producing columnar cells, compared with complete small-intestinal type I.
Which serum test reflects corpus atrophy?
A pepsinogen I to pepsinogen II ratio below about 3, typically paired with raised serum gastrin-17 in Japanese ABC-method screening.
Does H. pylori eradication reverse the cascade?
It reverses gastritis and interrupts progression best when given before metaplasia; established atrophy and metaplasia rarely regress fully, so surveillance continues.