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Bowel Cancer

From Mediwikis

3rd most common cancer (behing lung and breast) and 2nd most common cause of cancer death in the Western World.

Bowel cancer almost always arises in the large bowel and not the small bowel.

It is more common in the distal large bowel and rectum than in the proximal large bowel.

Risk Factors

Thought to Increase Risk

Thought to Decrease Risk

Male

Increasing age

High dietary fat

High alcohol consumption

Vegtables

Fibre

Vitamin C

Regular NSAIDs

Predisposing Conditions:

  • Inflammatory Bowel Disease - especially Ulcerative Collitis
  • FAP - Familial Adenomatous Polyposis
  • Presence of sporadic polyps - bowel cancer often arises in a polyp, but not all polyps contain cancer
  • Villous Adenomas - seen as a pre-malignant state

Syndromes including:

  • Gardner's
  • Turcot's
  • Peutz-Jegher's
  • Lynch Syndrome (HNPCC)

Pathology

Most bowel cancer occurs in the distal colon and rectum. There is often spread to the lymph nodes at presentation. Metastatic spread is often to the liver via the portal vein.

Presenting Features

  • Change in bowel habit
  • Weight loss
  • Pain
  • Iron deficiency anaemia
  • Melaena
  • Bowel obstruction/perforation (presenting as an emergency)

Investigations

  • Colonoscopy- To attain biopsy of tumour
  • CT/MRI scan to stage extent of disease
  • CEA - Carcinoembryonic Antigen - this is the tumour marker associated with bowel cancer, but it can also be raised in:
    • IBD, pancreatitis and heavy smokers

Staging

Classified according to Dukes Criteria:

  • A: Invasion into but not through the bowel wall (90% 5y survival)
  • B: Invasion through the bowel wall but not involving lymph nodes (70% 5-y survival)
  • C: Lymph node spread (30% 5-y survival)
  • D: Widespread metastases

Management

  • Surgery
  • Radiotherapy
  • Chemotherapy
  • Biological agents including Bevacizumab (Avastin)