Bowel Cancer Flashcards
How common is bowel cancer in terms of prevalence?
- 3rd most common in UK for men and women
Is bowel cancer more common in the western world or Asia and Africa?
- Western world
Is bowel cancer more common in white or black populations?
- white
2 in 3 bowel cancer patients are over the age of what?
- 60 years old
What is one of the most common lifestyle risk factors that we can change for bowel cancer that we need to be aware of?
- dietary fibre
What are the 3 risk risk factors for bowel cancer that cannot be changed?
- age
- genetics
- ethnicity
What are the 3 main reasons why we think dietary fibre reduces the risk of bowel cancer?
1 - increased SCFA production
2 - reduce stool transit time
3 - reduces secondary bile acid formation
What does neoplasia mean?
- new abnormal formation/growth of cells/tissue
- can be benign or malignant.
What are polyps?
- abnormal tissue growth (neoplastic)
- look like small, flat bumps or tiny mushroomlike stalks
What is dysplasia?
- abnormal cells within a tissue or organ
- due to abnormal growth or development of cells
Is neoplasia and dysplasia reversible?
- neoplasia = no
- dysplasia = yes
- dysplasia is precursor for neoplasia
How common are polyps in the lower GIT?
- very common
- 20-25% of population
Polyps are generally the precursors for what?
- majority of bowel cancers
What is an adenoma?
- adeno = gland of GIT
- adenoma - non-cancerous/benign tumour
Dysplasia can be beign or can be a precursor for malignancy. What are the terms used when describing dysplasia?
- low grade
- high grade (“pre-malignant”)
What is the adenoma-carcinoma sequence?
- stepwise progression from normal bowel mucosa to bowel cancer
- can take years
- hyperplasia, dysplasia, adenoma/polyp, carcinoma in situ to invasive carcinoma
What are adenomas strongly associated with?
- bowel cancer
Which part of the colon will the majority of bowel cancers occur in?
- 60-70% in left colon (predominantly sigmoid and rectum)
- 20-25% in right colon
At what age does the incidence of polyps peak?
- polyps = 60 years old
- bowel cancer = 71 years old
- generally predate cancer
Does the number of polyps increase the risk of bowel cancer and can polpys be removed?
- increased polyps = increased bowel cancer risk
- removal of polyps reduces bowel cancer risk
What is the Wilsons Screening Criteria?
- a criteria for screening
- emphasise the important features of any screening program
Why is it important to know about the adenoma-carcinoma sequence when it comes to the Wilsons Screening Criteria in relation to bowel cancer? (3 stages)
1 - identification of a pre-malignant phase (polyp)
2 - is there is a good and acceptable test (colonoscopy) to identify pre malignancy
3 - is there an agreed and acceptable treatment (polypectomy)
What does autosomal dominant mean?
- autosomal = gene in question is located on one of the numbered, or non-sex, chromosomes
- dominant means that a single copy of the disease-associated mutation is enough to cause the disease
What is Familial Adenomatous Polyposis (FAP)?
- autosomal dominant inherited disease
- causes adenomatous polyposis coli (APC) mutation (tumour supressor)
- results in uncontrolled cell growth and polyp formation
Why is the adenomatous polyposis coli (APC) gene so important in bowel cancer?
- it is a tumopur supressor gene
- important to stop abnormnal cell growth
What % of all bowel cancers does Familial Adenomatous Polyposis (FAP) account for?
- aprox 1%
In a patient with Familial Adenomatous Polyposis (FAP) how many polyps would they be expected to have by their teens?
- >100 polyps
In a patient with Familial Adenomatous Polyposis (FAP) by the time they are 30, what is the risk of bowel cancer?
- 100%
In a patient with Familial Adenomatous Polyposis (FAP) by the time they are 30 they are at a 100% risk of developing bowel cancer. What is therefore the treatment?
- proctocolectomy recommended by 20s
- this is complete removal of colon and rectum
In a patient with Familial Adenomatous Polyposis (FAP) by the time they are 30 they are at a 100% risk of developing bowel cancer and are generally offered a proctocolectomy (removal of colon and rectum) by their 20s. In addition, there are 3 main places where polyp formation must be screened for, where are these?
1 - stomach
2 - small bowel (especially duodenum)
3 - thyroid