Page 186 - Medicine and Surgery

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182 Chapter 4: Gastrointestinal system

Table 4.6 Dukes classification of colorectal carcinoma Anal squamous cell carcinoma
Dukes 5-year Definition
stage Tumour spread survival (%)
The anal canal is lined with stratified squamous epithe-
A Not extending through the >90 lium and thus is prone to development of epithelial de-
muscularis propria
B Extending through the 70 rivedtumours.
muscularis propria but no
node involvement Incidence
C Any nodal involvement 30
D Distant metastases 5 Much less common than rectal carcinoma.

Sex
In arecent study the use of faecal occult blood testing M > F

as screening has a positive predictive value was 11%
for cancer and 35% for adenoma. 48% of all detected
Clinical features
cancers were Dukes stage A (see Table 4.6).
Patients present with a localised ulcer or a wart like
growth, there is often associated bleeding and discharge.
Management Inguinal lymph nodes may be stony hard if spread has
Primaryresectionisthetreatmentofchoiceinfitpatients occurred. In female patients an ano-vaginal fistula may
(see also page 148). result in offensive vaginal discharge.
Tumours of the right and transverse colon require

righthemicolectomy and ileocolic anastomosis.
Investigations
Tumours of the descending colon are treated with left

Suspect lesions require biopsy.
hemicolectomy.
Tumours of the sigmoid colon are treated with a sig-

moid colectomy. Management
In all the procedures the associated mesentery and re- Treatment is by combined local radiotherapy and
gional lymph nodes are removed en bloc. chemotherapy rather than abdominoperineal resection.
Most rectal tumours are treated by anterior resection. Early metastases are frequent.
In very low rectal lesions an abdominoperineal (AP) re-
section with formation of a permanent colostomy in the
left iliac fossa may be required. Familial adenomatous polyposis
Resections may be curative or palliative, if resection
Definition
is not possible a bypass procedure may be carried out.
Familial adenomatous polyposis is a rare genetic condi-
Adjuvant chemotherapy based on 5-fluorouracil (5-FU)
tion in which patients develop multiple polyps.
is performed in patients with Dukes stage C (see below)
but has not been shown to be beneficial in Stage A or
B disease, or in elderly patients who have a higher in- Aetiology/pathophysiology
cidence of complications. Patients with limited hepatic This is an autosomal dominant condition in which there
metastases may benefit from resection of the metastases. is a defect in the adenomatous polyposis (apc) gene on
Rectal carcinomas are just as likely to recur locally the long arm of chromosome 5. Multiple polyps develop
as metastasise distantly, so treatment is best with local during childhood throughout the large bowel.
radiotherapy and adjuvant chemotherapy.
Clinical features
Prognosis Patients may be identified through screening of known
The overall 5-year survival rate is 40% but this depends relatives. The presence of multiple polyps may lead to
on Dukes staging (see Table 4.6). bleeding, diarrhoea and mucus discharge.