Carcinogenesis
Benign tumours – do not invade surrounding tissues
Malignant tumours – can directly invade adjacent tissues or enter blood and lymphatic channels. The
malignant genotype develops as a result of progressive acquisition of cancer mutations formation of
cancer stem cells.
Malignant tumours of the large intestine
Colorectal adenocarcinoma
Most common GI malignancy, lifetime risk ~5%
Pathological features
May occur as polypoid, ulcerating, stenosing, or infiltrative tumour mass
Majority are L side of colon and rectum (75%); rectum – 45%, descending sigmoid – 30%, transverse – 5%,
R-sided 20%
Algorithm for referral
Risk factors Urgent pathway (2WW)
- Male gender Patients > 40 w/ unexplained weight loss and
- Increasing age abdo pain or
- Family hx Patients > 50 w/ unexplained rectal bleeding or
- Westernised diet Patients > 60 w/
o High fibre = protective - IDA or
o High-energy, low-fibre, high-fat = risk - Change in bowel habit or
factors - Tests showing occult blood in faeces
- Aspirin thought to be protective
- Polyposis syndromes (FAP, Lynch syndrome, Consider suspected cancer referral in adults w/
Juvenile polyposis) rectal/abdo mass
- Previous hx of polyps or CRC
- Chronic UC or colonic CD Consider for adults < 50 w/ rectal bleeding and
any of the following unexplained symptoms
Clinical features - Abdo pain
Rectal location - Change in bowel habit
- PR bleeding (deep red, surface of stools) - Weight loss
- Change in bowel habit - IDA
- Difficulty with defecation
- Tenesmus
Descending-sigmoid location
- PR bleeding (typically dark red, mixed with stools)
- Change in bowel habit (often frequency, variable consistency, mucus PR, bloating, flatulence)
R sided location
- IDA may be only presentation
Emergency presentations
Up to 40% present as emergencies
- Large bowel perf. (colicky pain, bloating, bowels not opening)
- Perf with peritonitis
- Acute PR bleed
Population screening
, - Scotland – screening every 2 years for people aged 50-74 years
- Rest of UK – offered every 2 years for people aged 60-74 years
- Faecal immunochemical testing (FIT)
o Normal normal recall
Protocol for rectal bleeding outside 2WW
o Abnormal colonoscopy
Emergency admission for patients with profuse
rectal bleeding cause hypotension or Hb
Diagnosis and investigation
- Colonoscopy 1st line
Referral for patients with persistent unexplained
- CT colonography can be useful for
rectal bleeding and/or anorectal symptoms
investigation of altered bowel habit
resistant to local 1st line treatments
- Emergency presentations
o Commonly diagnosed by CT abdo
- Staging
o CT CAP, CT-PET
o Assessment of local extent Duke’s staging (5yr survival, %)
CT for colonic carcinoma A, confined to bowel wall only (75-90)
Pelvic MRI for rectal cancer B, through bowel wall (55-70)
o Colonoscopy or barium enema C, any with + lymph nodes (30-60)
o Tumour marker CEA no use for diagnosis D, any with metastases (5-10)
or staging but can be used to monitor
disease relapse if raised at diagnosis TNM
T 1-4 – stage of invasion through bowel
Management wall
Potentially curative – suitable for resectable tumours w/ N0/1/2 – No/ up to 4/ >4 lymph nodes
no evidence of metastases (or metastases potentially M0/M1
curable by liver/lung resection)
- Surgical resection (w/ lymphadenectomy) = only curative treatment
o R/transverse: R/extended R hemicolectomy
o L: L hemicolectomy
o Sigmoid/upper rectum: high anterior resection
o Lower rectum: low anterior resection/abdominoperineal resection (APER)
o Anorectal: APER w/ end colostomy. Some very superficial tumours can use trans-anal
endoscopic microsurgery (TEMS)
- Preoperative (neoadjuvant) chemoradiotherapy may be used to rectal cancer to chance of
curative resection
- Adjuvant chemo (5FU) offered for tumours with + lymph nodes or evidence of vascular invasion
- +/- hepatic/lung resection
May require de-functioning stoma –
where stoma is performed proximally to
anastomosis to allow anastomosis to rest
prior to use
Total/subtotal colectomy – may be used
for UC, polyposis (including FAP)
Total – end ileostomy
Subtotal – ileo-rectal anastomosis
*Involves excision of colonic mesentery,
ligation of arterial supply at origin, and
excision of all accompanying lymph
nodes*