Carcinoma of the Colon, Rectum and Anus Flashcards
What are the risk factors for colorectal carcinoma?
Family history Age Low dietary fibre/high fat diet (western) UC Smoking
What are the protective factors for colorectal carcinoma?
Fibre consumption
Exercise
HRT
Aspirin/NSAIDs
What is the genetic component contributing to colorectal carcinoma?
Familial adenomatous polyposis (FAP)
Hereditary non-polyposis colorectal cancer (HNPCC)
Describe FAP
Responsible for <1% of cancers
Due to tumour suppressor gene APC mutations
Describe HNPCC
Responsible for <5% of cancers
Germline mutations in mismatch repair genes
What cancer morphology is typical of colorectal carcinomas?
Adenocarcinomas (signet rings)
Where do most colorectal carcinomas occur?
Caecum & Ascending Colon - 15% Transverse Colon - 10% Descending Colon - 5% Sigmoid Colon - 25% Rectum - 45%
How do colorectal carcinomas first develop?
Polypoid mass w/ ulceration
Initial spread by bowel wall infiltration
How do colorectal carcinomas typically spread?
Through lymphatics/blood vessels
Metastasise to Liver primarily
Can spread transcoelomically
What are the common symptoms suggesting colorectal carcinoma?
Abdominal mass Abdominal pain Haemmorhage Perforation Fistula
How do R-sided colorectal carcinomas typically present?
Often asymptomatic
May present w/ IDA/weight loss
How do L-sided colorectal carcinomas typically present?
PR blood/mucus Altered bowel habit Tensemus Obstruction Mass on PR exam
How do anal carcinomas typically present?
Bleeding Pain Altered bowel habit Pruritis ani Masses/stricture
Describe Duke’s staging of colorectal carcinoma
Duke’s A - Tumours invade submucosa +/- muscularis propria
Duke’s B - Tumours invade past muscularis proria but no nodal involvement
Duke’s C - Regional lymph node involvement
Duke’s D - Distant metastases
What is the most common morphology of anal cancers?
SCC
Affect 1200 people/yr in the UK