Flashcards in Colorectal Cancer Deck (108)
How does the incidence of colorectal cancer differ from other cancers?
It is the third most common cancer in the UK
How does the mortality of colorectal cancer differ from other cancers?
It has the second highest mortality figures of any cancer
What is the occurrence of colorectal cancer strongly associated with?
What % of presentations of colorectal cancers are in patients in those >60 years?
Can colorectal cancers occur in patients 20-30 years of age?
Yes, particularly in inherited cancer syndromes
Where do colorectal cancers originate from?
The epithelial cells lining the colon or rectum
What is the most common type of colorectal carcinoma?
What are the rarer types of colorectal carcinoma?
How do most colorectal cancers develop?
Via a progression of normal mucosa to colonic adenoma (colorectal polyps), to invasive adenocarcinoma
How long can adenomas be present before becoming malignant?
10 years or more
What % of adenomas progress to adenocarcinomas?
What genetic mutations have been implicated in predisposing individuals to colorectal cancer?
Adenomatous polyposis coli (APC) gene
Hereditary non-polyposis colorectal cancer (HNPCC)
What is the APC gene?
A tumour suppressor gene
What does early APC gene mutation and inactivation result in?
Growth of adenomatous tissue
What condition is APC mutation responsible for the development of?
Familial adenomatous polyposis (FAP)
What happens in HNPCC?
Mutation to DNA mismatch repair genes lead to defects in DNA repair
What does HNPCC commonly account for?
The familial risk associated with colorectal cancer
What % of colorectal cancers are sporadic?
What is meant by sporadic in colorectal cancer?
Developing in people with no specific risk factors
What are the risk factors for colorectal cancer?
Age >60 years
Inflammatory bowel disease
Low fibre diet
High processed meat intake
High alcohol intake
What are the common clinical features of bowel cancer?
Change in bowel habit
When is progressive weight loss present in colorectal cancer?
Only with associated metastasis, or rarely sub-acute bowel osbtruction
What symptoms may be present with a right-sided colon cancer?
Mass in right iliac fossa
What symptoms may be present with a left-sided colon cancer?
Change in bowel habit or tenesmus
Mass in left iliac fossa/mass on PR exam
When should patients be referred for urgent investigations for suspected bowel cancer?
40 or older with unexplained weight loss and abdominal pain
50 or older with unexplained rectal bleeding
60 or older with iron-deficiency anaemia or changes in bowel habit
Positive occult faecal blood test
What are the differential diagnoses for colorectal cancer?
Inflammatory bowel disease
How can inflammatory bowel disease be differentiated from colorectal cancer?
The average age of onset is younger (20-40years)
Typically presents with diarrhoea containing blood and mucus
How is haemorrhoids differentiated from colorectal cancer?
Bright red rectal bleeding covering the surface of the stool
Rarely presents with abdominal discomfort or pain, altered bowel habits, or weight loss
How can diverticulitis be differentiated from colorectal cancer?
It is likely to cause systemic features of inflammation