Colorectal Cancer
Reference: OHCM 506, Lec Not Onc 100
Epidemiology
2nd most common cause of death due to cancer in the UK.
Risk Factors
-
Neoplastic polyps (tubular or villous adenomas)
-
Ulcerative colitis/Crohns
-
Familial Adenomatous Polyposis/Hereditary Non-Polyposis
Colorectal Cancer
-
Family history
-
(↓fibre diet is a controversial risk factor)
Pathology
95% are adenocarcinomas.
Clinical
L-sided (75%):
Melaena, change in bowel habit, obstruction, tenesmus, mass felt PR.
R-sided (15%):
Anaemia, abdminal pain, (constipation is not a feature because faeces
still watery in this part of the bowel).
Either side:
weight
loss/anorexia, mass, perforation, haemorrhage, fistula, jaundice
Differential
Diverticular disease, Inflammatory bowel disease, infective GI disease
Investigations
NB: screening has been proposed but is not currently underway.
-
Diagnostic
pathway
(simplest and least sensitive first): Faecal
occult blood → PR → proctoscopy → sigmoidoscopy → colonoscopy + biopsy
-
Bloods:
FBC (microcytic anaemia), LFTs (metasteses to liver), CEA (for
monitoring purposes)
-
Staging:
CXR, CT abdomen/lungs, PET scan
Spread
Local (colon, viscera), lymphatic, blood (liver, lung, bone),
transcoloemic
Dukes Staging Criteria
A:
Bowel
wall (90% 5 year survival)
B:
Through
wall (65% 5 year survival)
C:
Lymph
nodes (30% 5 year survival)
D:
Distant
(<10% 5 year survival)
Management
Curative
Just surgery for A and B.
Surgery + chemotherapy for C.
Surgery even possible with 3-5 liver metasteses together with
chemotherapy
Radiotherapy used only for rectal cancer to ↓recurrence.
Palliative
Chemotherapy
Details of Management
Surgery:
-
Liver/lymph node metasteses resected.
-
Left hemicolectomy for distal transverse or descending colon
-
Right hemicolectomy for caecal, ascending or proxima
colonl.
-
Sigmoid colectomy for sigmoid.
-
Anterior resection for low sigmoid/high rectal tumours and
anastomosis made.
-
Abdomino-perineal resection for low rectum, permanent
colostomy needed.
Prognosis
60% amenable to radical surgery. See also the Dukes criteria (above)
