Cancer Risk Reduction and Pathophysiology

Gastric Carcinoma

• Gastric carcinoma is the fourth leading cause of cancer death worldwide, with marked geographical variation in incidence.
• Highest incidence rates are found in China, Japan, Korea, Eastern Europe, and parts of South America, with rates of 40/100,000 males.
• In the UK, the incidence rate is 12/100,000 for men, and 50% lower in women.
• Incidence rises sharply after 50 years of age.

Pylori Eradication and Cancer Prevention

• Pylori eradication, especially before irreversible pre-neoplastic changes, reduces cancer risk in high-risk populations and is cost-effective.
• Diets rich in salted, smoked, or pickled foods and consumption of nitrites and nitrates may increase cancer risk.

Pathophysiology of Gastric Cancer

• Virtually all gastric cancers are adenocarcinomas arising from mucus-secreting cells in the base of gastric crypts.
• Most develop upon a background of chronic atrophic gastritis with intestinal metaplasia and dysplasia.
• Cancers are either ‘intestinal’, arising from areas of intestinal metaplasia, or ‘diffuse’, arising from normal gastric mucosa.

Distribution of Gastric Cancers

• In the developing world, 50% of gastric cancers develop in the antrum, 20-30% in the gastric body, and 20% in the cardia.
• In Western populations, proximal gastric tumours are becoming more common than those arising in the body and distal stomach.

Gastric Lymphoma

• H. pylori infection is closely associated with the development of low-grade lymphoma (extranodal marginal zone lymphomas of MALT type).
• EUS plays an important role in staging these lesions by accurately defining the depth of invasion into the gastric wall.

Treatment of Gastric Lymphoma

• Initial treatment of low-grade lesions confined to the superficial layers of the gastric wall consists of H. pylori eradication and close observation.
• High-grade B-cell lymphomas require a combination of rituximab, chemotherapy, surgery, and radiotherapy.

Prognosis of Gastric Cancer

• The overall prognosis is poor, with less than 30% surviving 5 years.
• The best hope for improved survival lies in more efficient detection of tumours at an earlier stage.

Other Tumours of the Stomach

• Gastrointestinal stromal cell tumours (GIST) arise from the interstitial cells of Cajal and are occasionally found at upper gastrointestinal endoscopy.
• These tumours are usually benign and asymptomatic but may occasionally be responsible for dyspepsia, ulceration, and gastrointestinal bleeding.