Colorectal

Question 1

Progression

Answer 1

Normal epithelium –> hyper-proliferative epithelium –> benign adenoma –> invasive carcinoma

Question 2

Most common type of tumour

Answer 2

Adenocarcinoma (90%)

• rectum = 40%
• sigmoid = 20%
• caecum
• colon

Question 3

RF

Answer 3

Western diet - red meat, high fat, low fibre,
IBD
Familial - HNPCC (10%), FAP, Gardner’s syndrome
Mutations that allow progression form benign –> carcinoma

Question 4

Clinical presentation

Answer 4

Altered bowel habit
Rectal bleeding
Weight loss
Vague abdominal pain

Iron deficient anaemia
Obstruction + tenesmus

Question 5

Investigations

Answer 5

1. DRE - 75% of rectal tumours detected
2. Colonoscopy
3. CT - allows staging
4. CEA raised (not reliable - raised in smokers, IBD, hepatitis etc)

Question 6

Management

Answer 6

1. Surgery
   - resection
   - stent (palliative to prevent obstruction)
2. Radiotherapy - primary for rectal
   - not used in colon as can damage local organs
3. Chemo (mainly 5-FU) - adjuvant
4. Cetuximab - targets EGFR - causes painful rash