Colorectal
carcinoma
Pathology
Two thirds in
carcinomas occur in the rectosigmoid area
Tumours is a usually
polypoid mass with ulceration
Spread is initially
by direct invasion of the bowel wall
Next it invades the lymphatics
and blood vessels with early spread to the liver
Widespread
metastases eg. lung can occur
Polyps may develop in
the colon which may become malignant
Familiar adenomatous
polyposis - 100% chance of malignancy developing between 20 - 40 years of age
Epidemiology
Adenocarcinoma is the
second most common malignancy in the
Average age on
diagnosis is 60 - 65
Aetiology
Uncommon in
traditional Africa and
Positively correlated
with meat and animal fat consumption
Bacterial flora is effected by diet
Certain bacteria
convert bile acids to carcinogens
Fibre is a factor
Several oncogenes
have been identified
Two to three times
greater chance of developing bowel cancer if first order relative is affected
Clinical features
Alteration in bowel
habits
Bleeding
Iron deficiency
anaemia
Possible pain
Intestinal
obstruction
Mass may be palpable
Weight loss
Liver metastases
cause hepatomegaly
Investigations
Enema followed by direct
observation - colonoscopy - biopsy
Barium enema
Ultrasound
Screening
Universal FOB
screening reduced mortality by 33%
Some recommend a
single flexible sigmoidoscopy at 55, especially in those with first or second
degree relatives affected
Treatment
Resection
End to end
anastomosis if possible
Colostomy
Additional
chemotherapy for more advanced cases
Overall survival
after 5 years is 30% but is 95% if treated when only involving the gut wall