Comprehensive Study Notes: Carcinoma of the Stomach (Ca Stomach) Summary & Study Notes

🧾 Overview & Incidence

Gastric cancer shows the highest incidence in Japan and a poorer prognosis in many western countries. It is primarily a disease of the elderly, with a male:female ratio ≈ 2:1. Incidence is higher in low socioeconomic classes and in eastern > western countries.

🔬 Pathogenesis (Correa model)

The classic pathway to intestinal-type gastric cancer is the Correa model: chronic gastritis → gastric atrophy → intestinal metaplasia → dysplasia → carcinoma in situ → invasive carcinoma. This sequence underlies many environmental and infectious etiologies.

🧫 Aetiology & Risk Factors

Multiple interacting factors increase risk:

• Dietary factors: high dietary nitrates (converted to nitrosamines by GI bacteria), salted/pickled/smoked foods, spices, grilled/BBQ meats (polycyclic hydrocarbons), alcohol, protein malnutrition, and deficiencies of vitamins/trace elements.

• Infection: Helicobacter pylori is a class I carcinogen and drives chronic atrophic gastritis → intestinal metaplasia → dysplasia → cancer.

• Predisposing conditions: atrophic or autoimmune gastritis, pernicious anaemia, prior gastric surgery (remnant/stump cancer), adenomatous gastric polyps (>2 cm), chronic benign gastric ulcer (biopsy after surgery), EBV infection, radiation exposure.

• Lifestyle & host factors: alcohol, smoking, blood group A (associated with hypoacidity and some diffuse-type features), family history (≈10%) and tumor suppressor gene mutations (e.g., p53).

🧬 Pathology — Types & Classification

• Early gastric cancer: tumour limited to mucosa and submucosa (T1, any N). Excellent cure rates (~95% for T1N0).

• Advanced gastric cancer: invades muscularis propria or beyond; often classified by Borrmann types.

• Lauren classification: two major patterns:

  • Intestinal type: gland-forming, localized, more common in older males, associated with intestinal metaplasia, better prognosis.
  • Diffuse type: infiltrative (linitis plastica), occurs in younger patients and females, associated with worse prognosis and genetic predisposition.

• Gross/macroscopic types: cauliflower (polypoid), ulcerative (most common), infiltrative/leather-bottle (linitis plastica), colloid and others.

• WHO histologic types: adenocarcinoma (papillary, tubular, mucinous, signet-ring), adenosquamous, squamous, undifferentiated.

• Differentiation (Broder’s grading): Grade I–IV reflecting percent gland formation / differentiation.

• Common sites: prepyloric/pyloric region (≈65%), body (25%), fundus (10%), OG junction and whole-stomach involvement possible.

🔁 Routes of Spread

• Direct extension: into stomach wall and adjacent organs (omentum, transverse colon, mesocolon, left liver lobe, pancreas).

• Lymphatic spread: follows gastric vessels to coeliac & para-aortic nodes, cisterna chyli → thoracic duct → left supraclavicular node (Virchow/Troisier’s sign).

• Haematogenous metastases: classically to L L B B — Liver, Lungs, Bones, Brain.

• Transcoelomic (peritoneal) spread: Krukenberg tumour (bilateral ovarian mucinous metastases), rectal shelf (Blumer), carcinomatosis with ascites, omental cake, Sister Mary Joseph’s nodule (umbilical metastasis), axillary nodes (Irish sign).

🩺 Clinical Features

• Early gastric cancer is often asymptomatic; screening (e.g., 2-yearly in high-risk populations) detects early lesions.

• Advanced disease mnemonic — LIONS:

  • Lump in epigastrium: hard, irregular, non-tender, fixed intra-abdominal mass.
  • Insidious onset of the 3 A’s: Anaemia (iron deficiency), Anorexia, Asthenia.
  • Obstruction: dysphagia for cardia/oesophageal involvement, gastric outlet obstruction for antral/pyloric tumours.
  • New dyspepsia after age 40 (often diffuse cancers).
  • Silent presentation with metastatic signs: left supraclavicular node, Sister Mary Joseph’s nodule, hepatomegaly/jaundice, cough/haemoptysis, bone pain, neurological signs, migratory thrombophlebitis (Trousseau’s syndrome).

• Complications include bleeding (haematemesis, melaena) and perforation causing peritonitis.

🔎 Investigations

• For diagnosis: OGD (endoscopy) with biopsy and cytology is the gold standard for visualization and histologic confirmation. Chromoendoscopy may help detect early lesions for endoscopic resection.

• Barium meal (double-contrast) can show polypoid (persistent filling defect), ulcerative (ulcer crater) or infiltrative (“leather bottle”) patterns.

• For staging:

  • Endoscopic ultrasound (EUS): best for assessing depth of invasion (T) and locoregional nodes (N).
  • CT chest & abdomen, PET-CT, and laparoscopy: assess distant metastasis (M) and peritoneal disease. Laparoscopy useful to detect occult peritoneal spread.
  • Targeted imaging: chest X-ray for lung metastases, abdominal ultrasound for liver lesions, CT head for brain, bone scan for skeletal metastases.

• Preoperative assessment: FBC/CBC, coagulation, group & match, renal function, LFTs, ECG.

📏 Staging (TNM summary)

• T: T1 (mucosa/submucosa) → T2 (muscularis propria) → T3 (serosa) → T4 (invasion of adjacent structures).
• N: N0 (no regional nodes), N1 (1–6 regional nodes), N2 (7–15), N3 (>15 nodes).
• M: M0 (no distant metastasis), M1 (distant metastasis present).

(Use formal TNM tables for precise stage grouping clinically.)

🛠 Management Principles

• Surgery is the only potential cure. Aim is en bloc resection of the primary with appropriate lymphadenectomy and reconstruction.

• Curative (radical) surgery: extent determined by tumour site and nodal status; margin clearance targets ~2 cm for early lesions and ~5 cm for advanced lesions when feasible. Options include distal, subtotal or total gastrectomy.

• Lymphadenectomy classification (Japanese D-levels):

  • D1: tumour + N1 nodes (limited nodal clearance).
  • D2: includes N2 nodes (more extensive; may involve splenectomy/pancreatic tail resections historically).
  • D3: extended nodal clearance beyond N2.

• Reconstruction: after distal gastrectomy → Billroth I or II; after subtotal/total gastrectomy → Roux-en-Y oesophagojejunostomy or gastrojejunostomy.

• Palliative surgery: palliative gastrectomy preferred when feasible; alternatives include gastrojejunostomy for obstructing antral cancer, endoscopic stenting for cardia/antral obstruction, and endoscopic dilatation.

• Chemotherapy: combination regimens (e.g., ECF: epirubicin, cisplatin, 5-FU) are used; neoadjuvant chemotherapy can improve resectability and survival in some cases.

• Radiotherapy: limited role for primary tumour but useful for palliation (e.g., painful bone metastases).

• Other options: endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for early lesions, targeted therapies (e.g., HER receptor antagonists) in selected cases.

♻️ Evidence of Incurability / Inoperability

• Distant haematogenous metastases, diffuse peritoneal involvement, N3 nodal disease, fixed unresectable structures, ascites, para-aortic nodes, liver secondaries, palpable extensive mass, Blumer shelf, supraclavicular (Virchow) node, Sister Mary Joseph node indicate poor surgical cure prospects.

📈 Prognosis

• Very favourable for T1 N0 M0 (≈95% 5-year survival when truly early and resected).
• Poor prognosis for M1 disease (≈10% 5-year survival).
• Overall prognosis depends on stage at diagnosis, histologic type (intestinal vs diffuse), resectability, and nodal involvement.

📌 Sister Mary Joseph’s Nodule

A firm, often vascular umbilical nodule representing metastasis from intra-abdominal malignancy (commonly stomach, colon, ovary, pancreas). Mechanisms include direct extension, haematogenous/lymphatic spread, or along embryonic ligaments (ligamentum teres, urachus, vitello-intestinal duct).

🔭 Recent Advances & Key Points

• Screening in high-risk populations improves early detection.
• EMR/ESD permit curative endoscopic therapy for selected early tumours.
• Neoadjuvant chemotherapy and improved perioperative care have improved outcomes.
• Consider genetic counselling and prophylactic gastrectomy in strong familial syndromes.

Overall, early detection and appropriate surgical management with tailored multimodal therapy offer the best chance for long-term survival.