• Colorectal Cancer

    by  • 27/05/2013 • Oncology

     

    1. PH issue in MEDCs
    2. Incidence: 20,000 deaths/yr/UK – and increasing!
    3. Conditions which predispose to CRC:
      1. o Adenomatous polyps of the colon
      2. Usually tubulovillous adenomas
      3. These polyps have potential to become malignant
      4. Larger polyps = more risk of cancer forming at site (<1cm polyps = 1-10% risk, >2cm = 35-55%)
      5. o Ulcerative Colitis:
      6. At increased risk of malignant change – should be offered 2-yearly surveillance colonoscopy with random biopsies taken to detect severe dysplasia
      7. o Family History: – depending on type of hx
      8. One 1st degree relative <45yo = 1:40 lifetime risk
      9. One 1st degree relative >45yo = 1:12
      10. Two 1st degree relatives (any age) = 1:8
      11. HNPCC = 1:2
      12. o Familial cancer syndromes:
      13. Familial adenomatous polyposis (FAP): have hundreds of polyps throughout colon evident from an early age. High risk of neoplasia – such that a prophylactic colectomy is advised aged ~20.
      14. Hereditary non-polyposis colon cancer (HNPCC): autosomal dominant, and a mutation of mis-match repair genes. Should be offered colonscopic screening
    4. Clinical features:
      1. o Proximal CRC (Caecumhepatic flexure): iron deficiency, weight loss, RIF mass, small bowel obstruction
      2. o Distal CRC (Left side of colon): altered bowel habit, PR bleeding, large bowel obstruction
      3. o Rectal CRC: tenesmus, fresh PR bleeding, mucus PR, altered bowel habit
    5. Staging of CRC (=Duke’s staging):
      1. o A: limited to bowel wall submucosa. Survival at 5yrs: 95-100%
      2. o B: penetrating to serosa level. 65-75%
      3. o C: LNs involved: 30-40%
      4. o D: distant mets. <1%
    6. Ix:
      1. o Barium enema: often the method by which the tumour is identified
      2. o Colonoscopy: ensure the entire bowel is checked to rule out synchronous tumours or polyps
      3.  
      1. o FBC: iron deficiency anaemia
      2. o Search for mets: LFTs/liver USS, CXR
      3. o Carcinoembryonic antigen (CEA): not useful for diagnosis but beneficial in monitoring patient’s response to tx and identification of disease relapse
    1. Mx:
      1. o Surgery: almost always required. Extent of resection depends on severity/site of tumour. Attempt to resect atleast 5cm of normal bowel either side of lesion, and clear regional LNs. Prognosis will then depend on histological grade of the tumour and Duke’s staging
      2. o CT: 5-flurouracil can improve outcome in Duke’s B and C.
      3. o RT: pre-operative RT to ‘down stage’ rectal tumours
      4. o Follow-up/secondary prevention: if prior history of CRC or tubulovillous adenoma – should undergo surveillance colonoscopy
      5. o Palliative approaches: self-expanding metal stents may be an option to relieve symptoms of obstruction. 
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