Gastric cancer

Introduction

Gastric cancer is an uncommon but aggressive malignancy of the stomach. It is often diagnosed at an advanced stage, with a high associated mortality. Adenocarcinoma is the most common histological subtype.

Peak Incidence

• Most commonly affects individuals aged 75 years and older.

Pathophysiology

• Arises from the gastric mucosa, most commonly in the antrum.
• Risk factors include chronic Helicobacter pylori infection, smoking, high salt intake, a diet low in fruits and vegetables, pernicious anaemia, and a family history.
• Intestinal-type is associated with chronic gastritis and follows a stepwise progression.
• Diffuse-type, including signet ring cell carcinoma, tends to be more aggressive and has a worse prognosis.

Symptoms

• Dysphagia (particularly for solids, if involving the gastro-oesophageal junction).
• Persistent nausea or vomiting.
• Epigastric or vague upper abdominal pain.
• Early satiety (feeling full quickly).
• Unintentional weight loss.
• Upper gastrointestinal bleeding:
  • Haematemesis (vomiting blood).
  • Melaena (black, tarry stools).

Signs

• Signs of upper gastrointestinal bleeding (e.g. pallor, melaena, haematemesis).
• Virchow’s node: palpable left supraclavicular lymph node.
• Sister Mary Joseph’s nodule: periumbilical metastatic deposit.
• Hepatomegaly and ascites in metastatic spread.
• Acanthosis nigricans (paraneoplastic sign in rare cases).

Diagnosis

Primary Investigation

• Oesophagogastroduodenoscopy (OGD) with biopsy – Confirms diagnosis and allows histological classification.
  • Presence of signet ring cells is associated with diffuse-type cancer and poorer prognosis.

Staging Investigations

• CT scan (chest, abdomen, pelvis) – Assesses local invasion and distant spread.
• PET-CT scan – Detects distant or occult metastases.
• Endoscopic ultrasound – May be used to assess depth of invasion and nodal involvement.
• HER2 testing on biopsy tissue – Determines eligibility for trastuzumab therapy.

Complications

• Metastatic spread to liver, lungs, brain, bones, and regional lymph nodes (e.g. coeliac, para-aortic).
• Gastric outlet obstruction – Occurs when the tumour obstructs the pyloric canal.
• Dumping syndrome – A complication of surgery leading to rapid gastric emptying and associated symptoms such as diarrhoea, dizziness, and abdominal cramping.

Management

Curative Treatment (Early or Localised Disease)

• Endoscopic mucosal resection – For very early-stage tumours confined to the mucosa.
• Surgical resection:
  • Partial gastrectomy – For tumours in the distal stomach.
  • Total gastrectomy – For extensive or proximal tumours.
• Perioperative chemotherapy – Standard of care to improve outcomes in resectable disease.
• Targeted therapy:
  • Trastuzumab for HER2-positive tumours.
  • Other agents may be considered in clinical trials.

Palliative Treatment (Advanced or Metastatic Disease)

• Systemic chemotherapy – To prolong survival and alleviate symptoms.

• Palliative radiotherapy – For bleeding or pain control.

• Nutritional and supportive care – Optimising quality of life, managing cachexia, and controlling symptoms.