Gastric Cancer
Summary
Gastric cancer is the 5th most common cancer worldwide and the 3rd leading cause of cancer death. The vast majority (95%) are adenocarcinomas. While incidence is declining in the West (due to H. pylori eradication and refrigeration), it remains a major killer due to late presentation. The strongest risk factor is chronic Helicobacter pylori infection (a Group 1 Carcinogen). Symptoms are often vague ("indigestion") until locally advanced. Diagnosis requires Gastroscopy (OGD) and biopsy. Curative treatment involves radical gastrectomy with D2 lymphadenectomy and peri-operative chemotherapy (FLOT regimen). [1,2]
Key Facts
- Silent Progression: The stomach is distensible. Tumours can grow large without causing obstruction.
- Linitis Plastica: "Leather Bottle Stomach". A diffuse, infiltrating type of cancer where the stomach wall becomes rigid and non-distensible. Prognosis is very poor.
- Lauren Classification:
- Intestinal Type: Associated with H. pylori, old age, males. Forms glands.
- Diffuse Type: Genetic (CDH1), young, females. Signet ring cells. Early spread.
- Metastatic Signs:
- Virchow's Node: Left supraclavicular node (Troisier's sign).
- Sister Mary Joseph Nodule: Umbilical nodule.
- Krukenberg Tumour: Drops down to the Ovary.
- Blumer's Shelf: Mass in Pouch of Douglas felt on PR.
Clinical Pearls
The "Indigestion" Trap: PPIs (Omeprazole) can heal the superficial ulceration over a cancer, masking symptoms while the tumour grows underneath. STOP PPIs for 2 weeks before endoscopy to avoid false negatives.
Blood Group A: Historically linked to Gastric Cancer (A for Achlorydria/Adenocarcinoma). Blood Group O is linked to Duodenal Ulcers (O for Over-production of acid).
Early Satiety: "I eat half a sandwich and feel full." This is a ominous sign of Linitis Plastica (stomach cannot stretch).
Hereditary Diffuse Gastric Cancer: Families with CDH1 mutation (E-cadherin). Lifetime risk >80%. Prophylactic total gastrectomy is recommended in 20s.
Incidence
- High in East Asia (Japan, Korea, China), Eastern Europe, South America.
- Male > Female (2:1).
- Peak age 60-80.
Risk Factors
- Infection: H. pylori, Epstein-Barr Virus (EBV).
- Diet: Salt, Nitrates (cured meats, pickling), Smoking. (Refrigeration is protective - fresh veg).
- Conditions: Pernicious Anaemia (atrophic gastritis), Previous partial gastrectomy (>15 years later).
- Genetics: Lynch Syndrome, FAP, Li-Fraumeni, CDH1.
Correa Cascade (Intestinal Type)
- Normal Mucosa.
- Chronic Gastritis (H. pylori).
- Atrophic Gastritis (Loss of glands).
- Intestinal Metaplasia (Stomach looks like bowel).
- Dysplasia.
- Adidascarcinoma.
Location
- Proximal (Cardia): Rising incidence (Obesity/Reflux related). Behaves like Oesophageal cancer.
- Distal (Antrum/Pylorus): Falling incidence (H. pylori related).
Symptoms
- Abdomen: Epigastric mass (late). Hepatomegaly. Ascites.
- Neck: Virchow's node.
- Rectal (PR): Blumer's shelf.
Endoscopy (Gold Standard)
- OGD: Visualise and Biopsy (take 6-8 bites).
- EUS (Endoscopic Ultrasound): For T-staging (depth of invasion) and N-staging.
Staging
- CT Chest/Abdo/Pelvis: Distant metastases (Liver, Lung, Peritoneum).
- Staging Laparoscopy: Mandatory for potentially curative cases >T1b.
- Why? CT misses small peritoneal seedlings (peritoneal carcinomatosis) in 20-30% of patients. If present, surgery is futile (Disease is Stage IV).
Biology
- HER2 Testing: For Trastuzumab eligibility in advanced disease.
- MMR Status: For Immunotherapy (Checkmate-649).
Management Algorithm
GASTRIC ADENOCARCINOMA
↓
CT + LAPAROSCOPY
↓
┌─────────────┴─────────────┐
METASTATIC LOCALISED (>T1)
(Stage IV) (Stage IB-III)
↓ ↓
PALLIATIVE CHEMO PERI-OPERATIVE CHEMO
(Platinum/Fluoropyr) (FLOT x 4 cycles)
(+/- Trastuzumab) ↓
RE-STAGE
↓
SURGERY
(Gastrectomy D2)
↓
POST-OP CHEMO
(FLOT x 4 cycles)
1. Curative Surgery
- Total Gastrectomy: For Proximal/Mid-body tumours. (Roux-en-Y reconstruction).
- Subtotal Gastrectomy: For Distal (Antral) tumours.
- Lymphadenectomy: D2 dissection (removing nodes along hepatic/splenic arteries) is standard of care (better survival than D1, confirmed by Dutch trials).
2. Chemotherapy
- Peri-operative: The MAGIC trial (ECF) and FLOT4 trial (FLOT) established that chemo before and after surgery improves survival compared to surgery alone.
- Standard: FLOT (Fluorouracil, Leucovorin, Oxaliplatin, Docetaxel).
3. Endoscopic Resection (ESD/EMR)
- Only for T1a (Mucosa only), non-ulcerated, less than 2cm, well differentiated. Very early cancers (common in Japan screening, rare in West).
4. Palliative
- Stenting: For pyloric obstruction or cardia dysphagia.
- Chemotherapy: Extends life / Quality of life.
- Radiotherapy: For bleeding/pain.
Post-Gastrectomy Syndromes
- Dumping Syndrome:
- Early: Hyperosmolar load hits jejunum -> Water shift -> Bloating/Diarrhoea/Dizziness.
- Late: Rapid sugar absorption -> Insulin spike -> Hypoglycaemia (2 hours later).
- B12 Deficiency: Loss of Intrinsic Factor. Needs IM B12 injections for life.
- Weight Loss: Small reservoir.
- Overall 5-year survival: ~20-30% (West).
- Stage 1 (Japan): >90%.
- Stage 4: less than 6-12 months.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| NG83 | NICE (2018) | Urgent OGD for dysphagia or weight loss >55. D2 gastrectomy is standard. |
| Gastric Cancer | ESMO | FLOT is the standard of care for peri-operative chemotherapy. |
Landmark Studies
1. MAGIC Trial (2006)
- Intervention: Peri-operative ECF chemo vs Surgery alone.
- Result: 13% improvement in 5-year survival with chemo.
- Impact: Changed practice from "Surgery First" to "Chemo First".
2. FLOT4 Trial (2019)
- Intervention: FLOT vs ECF (MAGIC regimen).
- Result: FLOT superior (Median survival 50 months vs 35 months).
- Impact: FLOT became the new global standard.
What is Gastric Cancer?
It is a cancer of the cells lining the stomach. It is often linked to a stomach bug called H. pylori which causes ulcers, or bad diet/smoking.
Why does it happen?
Long term irritation (from the bug or acid) changes the stomach lining until the cells go rogue and turn cancerous.
The Treatment
If caught early, we try to cure it. This involves strong chemotherapy to shrink the tumour, followed by a major operation to remove the whole stomach (Total Gastrectomy).
Can I live without a stomach?
Yes. The surgeon joins the gullet (oesophagus) directly to the small bowel. You can still eat, but you have to eat "little and often" because you don't have a storage bag anymore. You will also need Vitamin B12 injections every 3 months for life.
Primary Sources
- NICE Guideline NG83. Oesophago-gastric cancer: assessment and management in adults. 2018.
- Cunningham D, et al. Perioperative chemotherapy versus surgery alone for resectable gastroesophageal cancer (MAGIC). N Engl J Med. 2006;355:11-20. PMID: 16822992.
- Al-Batran SE, et al. Perioperative chemotherapy with fluorouracil plus leucovorin, oxaliplatin, and docetaxel versus fluorouracil or capecitabine plus cisplatin and epirubicin for locally advanced, resectable gastric or gastro-oesophageal junction adenocarcinoma (FLOT4). Lancet. 2019;393:1948-1957. PMID: 30982686.
Common Exam Questions
- Surgery: "Standard lymphadenectomy for curative gastric cancer?"
- Answer: D2 (D1 is insufficient, D3 is too morbid).
- Oncology: "Regimen for peri-operative chemo?"
- Answer: FLOT.
- Pathology: "Signet ring cells seen on biopsy. Type?"
- Answer: Diffuse Type (highly aggressive, Linitis Plastica).
- Nutritional: "Patient post-gastrectomy has tingling in feet and macrocytic anaemia. Cause?"
- Answer: B12 deficiency (Loss of Intrinsic Factor).
Viva Points
- Virchow's Node: Why left side? Thoracic duct drains abdomen and enters junction of Left Subclavian/IJ Vein.
- H. pylori mechanism: Urease produces ammonia (neutralises acid to survive). CagA toxin induces inflammation.
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