Bowel Cancer Flashcards
1
Q
How common is bowel cancer in terms of prevelence?
A
- 3rd most common in UK for men and women
2
Q
Is bowel cancer more common in the western world or Asia and Africa?
A
- Western world
3
Q
Is bowel cancer more common in white or black populations?
A
- white
4
Q
2 in 3 bowel cancer patients are over the age of what?
A
- 60 years old
5
Q
What is one of the most common lifestyle risk factors that we can change for bowel cancer that we need to be aware of?
A
- dietary fibre
6
Q
What are the 3 risk risk factors for bowel cancer that cannot be changed?
A
- age
- genetics
- ethnicity
7
Q
What are the 3 main reasons why we think dietary fibre reduces the risk of bowel cancer?
A
1 - increased SCFA production
2 - reduce stool transit time
3 - reduces secondary bile acid formation
8
Q
What does neoplasia mean?
A
- new abnormal formation/growth of cells/tissue
- can be benign or malignant.
9
Q
What are polyps?
A
- abnormal tissue growth (neoplastic)
- look like small, flat bumps or tiny mushroomlike stalks
10
Q
What is dysplasia?
A
- abnormal cells within a tissue or organ
- due to abnormal growth or development of cells
11
Q
Is neoplasia and dysplasia reversible?
A
- neoplasia = no
- dysplasia = yes
- dysplasia is precursor for neoplasia
12
Q
How common are polyps in the lower GIT?
A
- very common
- 20-25% of population
13
Q
Polyps are generally the precursors for what?
A
- majority of bowel cancers
14
Q
What is an adenoma?
A
- adeno = gland of GIT
- adenoma - non-cancerous/benign tumour
15
Q
Dysplasia can be beign or can be a precursor for malignancy. What are the terms used when describing dysplasia?
A
- low grade
- high grade (“pre-malignant”)
16
Q
What is the adenoma-carcinoma sequence?
A
- stepwise progression from normal bowel mucosa to bowel cancer
- can take years
- hyperplasia, dysplasia, adenoma/polyp, carcinoma in situ to invasive carcinoma
17
Q
What are adenomas strongly associated with?
A
- bowel cancer
18
Q
Which part of the colon will the majority of bowel cancers occur in?
A
- 60-70% in left colon (predominantly sigmoid and rectum)
- 20-25% in right colon
19
Q
At what age does the incidence of polyps peak?
A
- polyps = 60 years old
- bowel cancer = 71 years old
- generally predate cancer
20
Q
Does the number of polyps increase the risk of bowel cancer and can polpys be removed?
A
- increased polyps = increased bowel cancer risk
- removal of polyps reduces bowel cancer risk
21
Q
What is the Wilsons Screening Criteria?
A
- a criteria for screening
- emphasise the important features of any screening program
22
Q
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)
A
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)
23
Q
What does autosomal dominant mean?
A
- 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
24
Q
What is Familial Adenomatous Polyposis (FAP)?
A
- autosomal dominant inherited disease
- causes adenomatous polyposis coli (APC) mutation (tumour supressor)
- results in uncontrolled cell growth and polyp formation
25
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
26
What % of all bowel cancers does Familial Adenomatous Polyposis (FAP) account for?
- aprox 1%
27
In a patient with Familial Adenomatous Polyposis (FAP) how many polyps would they be expected to have by their teens?
- \>100 polyps
28
In a patient with Familial Adenomatous Polyposis (FAP) by the time they are 30, what is the risk of bowel cancer?
- 100%
29
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
30
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
31
In the 2 hit hypothesis of Familial Adenomatous Polyposis (FAP) how do cells begin to form polyps that ultimately lead to bowel cancer?
- 1 copy of faulty APC gene is inherited = **_1ST HIT_**
- 1 mutated allele of gene mutation is present in all cells in the body
- eventually the normal allele will become mutated, this is referred to as the **_2nd HIT_**
32
In the 2 hit hypothesis of patients who do not have Familial Adenomatous Polyposis (FAP) how do cells begin to form polyps that ultimately lead to bowel cancer?
- no APC mutation present at birth
- large bowel cells of crypts proliferate and mutation occurs = **_1ST HIT_**
- mutation occurs in daughter cells containing 1st hit mutation = **_2nd HIT_**
33
What is Lynch syndrome?
- an inherited condition
patients at increased risk of colon cancer, endometrial cancer and several other cancers
34
What causes Lynch syndrome?
- mutations in the DNA mismatch repair genes
- screens repairs, erroneous insertions, deletions, and mis-incorporation of bases that can arise during DNA replication and recombination
- can also repair DNA damage
35
In Lynch syndrome are genes always due to family history?
- no, but can be
- 20% are new genes not passed along by family
36
How common is Lynch syndrome in bowel cancer?
- 3% of all bowel cancers
- more commonly affects the right colon
37
What is the Amsterdam criteria?
- diagnostic criteria used by doctors
- helps identify families who are likely to have Lynch syndrome
38
The Amsterdam criteria is a diagnostic criteria used by doctors to helps identify families who are likely to have Lynch syndrome. What is the criteria?
- _\>_3 or more relatives with Lynch associated tumour (
- one affected relative must be first-degree relative of the other two
- two or more successive generations affected
- at least one cancer before the age of 50
- FAP excluded in cases of CRC
39
When did bowel screening begin and how was it originally screened?
- 2006
- based on Faecal Occult Blood Testing (FOBT)
- poor sensitivity and specificity
40
Bowel screening is now routinely performed. What age are patients generally screened and how are patients screened?
- one off test at the age of 55 years old
- flexible sigmoidoscopy
41
Bowel screening is now routinely performed. Patients _\>_55 will be screened for colon cancer using flexible sigmoidoscopy. What is being screened for and what % of cancers are generally missed?
- screening for polyps
- 25% of cancers are missed
42
As of june 2018 what is now the tool used for bowel cancer screening?
- Quantitative Faecal Immunohistochemical Test (qFIT)
43
As of june 2018 the Quantitative Faecal Immunohistochemical Test (qFIT) is the chosen test for bowel cancer. How does the qFIT work?
- detects human globin in stool
- essentially microscopic blood
44
As of june 2018 the Quantitative Faecal Immunohistochemical Test (qFIT) is the chosen test for bowel cancer. What age is this generally offered to and is this annual?
- offered to 60-74 years olds
- performed every 2 years
45
As of june 2018 the Quantitative Faecal Immunohistochemical Test (qFIT) is the chosen test for bowel cancer. It is generally given to patients aged between 60-74 years old. Can patients \>75 years old request qFIT?
- yes
- can request it every 2 years
46
If a patient has a positive test for a qFIT, what investigation would they then have?
- colonoscopy
47
What is a mjaor pitfall of any screening programme?
- bias
- only motivated patients will be screened even is asymptomatic
48
When screening patients for bowel cancer, how long do they generally live longer for?
- 4 years
- BUT still dont improve their outcomes
49
What is the major problem of the NICE symptoms as a predictor of bowel cancer?
- poor predictive value
50
The NICE symptoms as a predictor of bowel cancer are generally poor (3-4%), what has a higher predictive power?
- using multiple symptoms combined
51
What is a contraindication for the qFIT?
- rectal bleeding
52
When using the qFIT, what is the normal cut off levels?
- _\<_10µg Hb/g faeces
53
What is a higher qFIT score a predictor of?
- bowel cancer
54
Why is colonoscopy the gold standard for lower GIT bowel screening?
- able to go from rectum to end of small intestines
- diagnostic = confirm prescence of polyps or tumour
- therapeutic = removal of polyps
55
The colonoscopy the gold standard for lower GIT bowel screening. However, what are the negatives of this investigation?
- can be painfull and cause bleeding
- risk of perforation (1:2000)
- required GIT cleansing which is not pleasant
56
The colonoscopy is the gold standard for lower GIT bowel screening. However, flexible sigmoidoscopy can also be used. Why is this sometime preferred?
- less bowel cleansing required
- reduced risk of perforation
57
Why can virtual colonscopy be useful when screening patients for bowel cancer?
- contrast die used with CT scan
- low perforation rate (1:10,000)
58
A virtual colonscopy can be useful when screening patients for bowel cancer, but what are the 2 major downsides to using this approach?
- not therapeutic so patients may still require 2 tests
- high doses of radiation
59
Bowel cancers are very heterogenous. Grouping tumours together has 3 major benefits, what are they?
1 - treatment
2 - prognosis
3 - research - language that can translate internationally
60
What is the classification/grading approach for bowel cancers?
- TNM
- T = tumour size
- N = nodal involvement
- M = metastatic
61
When looking at the 4 stages of cancer, do stage 1 or stage 4 patients live longer?
- stage 1
62
Do younger or older patients do better once diagnosed with bowel cancer?
- older do better
63
Can co-morbidities be a predictor of outcomes in a patient diagnosed with bowel cancer?
- yes
- more co-morbidities = poorer outcome
64
Are all metastatic bowel cancers the same?
- no
65
What organ in the body is almost like a filter for metastatic bowel cancers?
- liver
- portal blood from GIT travels into the liver
- if liver is able to filter or keep metastises in the liver then it will not spread to the rest of the body
66
If bowel cancer becomes metastatic, generally it will enter the portal circulation and travel to the liver, where it tends to be trapped in the liver causing liver cancer. Why is this a good thing?
- liver can regenerate
- need as little as 30%
67
If bowel cancer becomes metastatic, generally it will enter the portal circulation and travel to the liver, where it tends to be trapped in the liver causing liver cancer. Removal of the liver metastases can result in long term survival. What is the 5 year survival rate?
- 40-60% 5 year survival
68
If a patient is diagnosed with bowel cancer they can undergo surgery to try and remove the tumour. What are the basic principles of this surgery?
- remove the cancer with clear margins
- removal of local lymph nodes for staging
- restoration of intestinal continuity (normal bowel or stoma)
69
What is local and regional treatment in bowel cancer?
- local = region where cancer is present (surgery, radiotherapy)
- systematic = rest of the body (chemotherapy)
70
Radiotherapy is a local treatment, meaning it is used to treat the local enviormnent where the cancer is present. This form of treatment must specifically target the same area each time. What type of bowel cancer is this treatment generally reserved for and why?
- rectal cancer as it is fixed
- rest of bowel is mobile and difficult to treat
71
In bowel cancer radiotherapy is generally reserved for rectal cancer. What effect does radiotherapy have on rectal cancer?
- generally for making tumours small prior to surgery
- 10-15% of patients have complete response rate
72
Of all the treatment options for bowel cancer, what is the only systemic treatment option?
- chemotherapy drugs
73
Chemotherapy drugs are the only systemic treatment options for bowel cancer. is this therapy generally used in isolation?
- no
- combined with surgery and radiotherapy
- significant side effects
74
If a patient has not been diagnosed with bowel cancer, but they present at A&E with acute presentation with lower GIT symptoms, what is the most likley cause?
- bleeding
- bowel obstruction
- bowel perforation
- fistula formation
- infection/abscess
75
If a patient has not been diagnosed with bowel cancer, but they present at A&E with acute presentation with lower GIT symptoms, what are the most common treatments?
- removal of tumour
- remove colon
- insert stent (means less invasive surgery required)
