Gastric Cancer

Background / Epidemiology

• Fourth leading cause of cancer death worldwide; poor prognosis (30% 5-year
• Incidence in the UK is ~12/100,000 in men (more common in Eastern Asia; Eastern Europe and South America); more common in men than women (2:1)

Pathophysiology

• H pylori infection associated with chronic atrophic gastritis/mucosal atrophy (thought to be involved in 60-70%)
  • H pylori usually located in the stomach body (cf peptic ulcer disease where H pylori is usually situated in the antrum) causing decreased acid production
    • However, the majority of tumours are found in the antrum (50%) rather than the body (20-30%)
• Other risk factors include smoking, alcohol excess, poor diet (salt rich; vitamin deplete)
  • Patients with pernicious anaemia (autoimmune gastritis); Menetrier’s disease; FAP and other inherited conditions e.g HDC1 mutations; CDH1 mutations
• Majority of tumours are adenocarcinoma (from mucous secreting cells of gastric crypts)- see below for other types

Presentation

• Upper abdominal pain and/or dyspepsia with weight loss
  • Occasionally nausea, dysphagia and malaena
  • Enlarged Virchow’s node is actually quite rare; although lymphadenopathy is a red flag
• Some patients will also present with signs of anaemia (an unexplained iron-deficiency anaemia should be investigated with scopes)
• Persistent vomiting, jaundice, odynophagia are other red-flag to consider

Investigations

• All patients >55 with new onset dyspepsia and weight loss (or other red flags) should have urgent upper GI endoscopy
  • Any lesions should be biopsied and (if malignant) staged
    • Staged by depth of invasion
      • T1- superficial to the muscularis propria
      • T2- invades muscularis propria
      • T3- invades subserosal connective tissue
      • T4- through serosa (visceral peritoneum) or adjacent structures
  • CT and laparoscopy for staging

Management

• Surgical resection/gastrectomy (radical curative treatment) + chemotherapy
• Palliative chemotherapy can prolong survival

MALT (Mucosa associated lymphoid tissue) Lymphoma

• Also associated with H pylori
• Characteristic histopathology- lymphoid tissue
• Presents similarly to adenocarcinoma
• Low grade tumours can be observed conservatively (+ H pylori eradication); High grade tumours should be treated as high grade lymphoma i.e. rituximab, chemo/radiotherapy, or surgery

Gastrointestinal stromal cell tumours (GIST)

• Arise from connective (stromal) tissue of the stomach
• Many asymptomatic but may cause dyspepsia, ulceration, and GI bleeding
• Can be removed by endoscopy if small and surgery if large (>2cm)
  • Very large tumours may be treated with imatinib (these tumours express tyrosine kinase receptors- imatinib antagonises the receptor and inhibits action); either palliatively or neo-adjuvantly

Carcinoid tumours

• Associated with long-standing pernicious anaemia
• Benign tumours of neuro-endocrine cells (may be multiple but rarely invasive)
• Generally have a good prognosis