Bowel Cancer (L12) Flashcards
1
Q
What is bowel cancer?
A
Cancer of the large intestine
2
Q
What is the epidemiology of bowel cancer?
A
- Higher prevalence in in Western world compared to Asia and Africa
- Affects men and women equally
3
Q
What are the risk factors of bowel cancer?
A
- Migration from a low risk country to a high risk country
- Foods rich in red meat and fat
- Lack of vegetables, fruit and fibre
- Lack of physical activity
- High BMI
- Ulcerative coliits
- Crohn’s disease
- Old age
- Family history
- Previous history of bowel cancer
4
Q
How does a high fibre diet reduce bowel cancer?
A
- Increases formation of short chain fatty acids, which promote healthy gut bacteria
- Increases the bulk of stool, reducing the transit time of stool (so carcinogens have shorter contact with bowel mucosa)
- Reduces secondary bile acid formation (which is carcinogenic)
5
Q
What is a polyp?
A
- Protrusion into a hollow viscus (singular for viscera)
- It can be benign, adenoma or malignant
- In bowel cancer screening, a polyp can either be innocent or pre-cancerous. If it is cancerous then it isn’t a polyp
6
Q
What is an adenoma?
A
A pre-cancerous lesion
7
Q
What is dysplasia?
A
- When the cells have the features of cancer but do not invade other cells
8
Q
What are the two grades of dysplasia?
A
- Low grade which is when there are early pre-cancerous features
- High grade which is when there are advanced pre-cancerous features and they have a high risk of invasion if they aren’t removed.
9
Q
What is the adenoma-carcinoma sequence?
A
A stepwise progression to bowel cancer, starting from normal mucosa, to an adenoma then to cancer
10
Q
What is the evidence for the adenoma-carcinoma sequence?
A
- Populations with a high prevalence of adenomas have a high prevalence of cancer
- Distribution of adenomas in the large bowel mirrors the distribution in bowel cancer
- Risk of cancer is directly related to the number polyps
- Removal of adenomas reduces the incidence of bowel cancer
11
Q
What does FAP stand for?
A
Familial Adenomatous Polyposis
12
Q
What is FAP?
A
Autosomal dominant disease that leads to an excessive number of polyps, which can become malignant
