Gastric

# Gastric Cancer: The Infection Connection

## Introduction: Declining but Not Defeated
Once the leading cancer killer, gastric cancer incidence has decreased 80% in developed nations due to refrigeration and reduced salt-preserved foods. However, it remains the fourth most common cancer globally, with 1 million new cases annually. The Lauren classification distinguishes intestinal-type (environmentally-driven) from diffuse-type (genetic) carcinomas, with profoundly different prognoses.

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## Causes and Risk Factors: H. pylori Centrality

### Primary Cause
- **Helicobacter pylori**: Responsible for 89% of non-cardia gastric cancer
- Pathogenic mechanisms:
  - Chronic inflammation → atrophy → metaplasia → dysplasia
  - CagA virulence factor disrupts cell signaling

### Contributing Factors
- **Dietary Carcinogens**: Nitrosamines in smoked/preserved foods
- **Autoimmune Gastritis**: Pernicious anemia association
- **Epstein-Barr Virus**: 10% of gastric cancers

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## Prevention Strategies: Eradication and Surveillance

### H. pylori Management Cascade
1. **Test-and-Treat**: All patients with dyspepsia
2. **Confirmatory Testing**: Urea breath test post-treatment
3. **Surveillance Endoscopy**: For high-risk populations

### Endoscopic Screening Protocol
| Population | Screening Strategy |
|------------|-------------------|
| General (Low Incidence) | No routine screening |
| High Risk (East Asia) | Biennial endoscopy from age 40 |
| Hereditary Diffuse GC | CDH1 testing, prophylactic gastrectomy |

### Nutritional Prevention
- Fresh fruits/vegetables (vitamin C)
- Green tea polyphenols
- Reduced salt intake (<5g/day)