Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 4 > case 4 - bowel cancer part 2 > Flashcards

case 4 - bowel cancer part 2 Flashcards

1
Q

what is the form of bowel cancer that normally develops

A

adenocarcinoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the rare family diseases

A

FAP
HNPCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the epidemiology of bowel cancer

A

3rd most common cancer and the second most common cause of UK cancer deaths
56% of presentations are those in >70 year olds
Most are found in the rectum
Least likely is the descending colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why is red meat a risk factor for bowel cancer

A

high levels of N-nitros compounds which are carcinogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what family history poses a risk for bowel cancer

A

neoplastic adenomatous polyps
colorectal cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the left sided bowel cancer presentations and what is it a disorder with

A

disorder with storage

bleeding/mucus
Altered bowel habit
Tenesmus (continual feeling of needing to evacuate the bowel)
Abdominal mass
Perforation
Haemorrhage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the features of right sided bowel cancer and what is it a disorder with

A

disorder with absorption

weight loss
Reduced haemoglobin
Abdominal pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the blood test used for bowel cancer and what are the results

A

Full blood count (indicate low serum levels (microcytic anaemia))
Serum proteins
Calcium - check for metastatic hypercalcemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the liver function test and what does it show

A

Bilirubin - colorectal cancer liver metastasis causes severe hyperbilirubinaemia
Alkaline phosphatase (ALP) - ALP levels elevated with liver metastasis of colorectal cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the kidney function test

A

creatine - creatine levels elevated with kidney metastasis of CRC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the barium enema test

A

test used to identify problems in the colon, such as polyps, inflammation, narrowing of the colon, tumours etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the liquid and what does it do that is used in the barium enema test

A

A thick liquid (containing barium) is placed in the lower gut via the rectum
This coats the mucosal lining of the colon, thus highlighting the colon in an X-ray
Characteristic findings are indicative of pathology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what kind of sign does colon cancer leave

A

an applecore sign

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what does chemotherapy reduce

A

duke’s C mortality by about 25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is Fluorouracil

A

a pyrimidine analog that is an antineoplastic antimetabolite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does an antimetabolite do

A

prevents purine/pyrimadine from incorporating into the DNA during the S phase, stopping normal development and division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does fluorouracil do

A

Fluorouracil blocks the enzyme which converts the cytosine nucleotide into the deoxy derivative
Fluorouracil inhibits the incorporation of the thymidine nucleotide into the DNA strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the mechanism of action of fluorouracil

A

is converted in cells to 5-fluoro-2’5’ monophosphate (5-FdUMP) and 5-fluurouradine-5’-triphosphate (FUTP), its metabolites

5-dUMP incorporates into the DNA of fast growing cells in the body

Here, it interferes with DNA synthesis by blocking thymidylate synthesis

Normally, thymidylate synthetase converts uracil into thymidylate

Blocking this enzyme inhibits the synthesis of thymidylate

This means that thymidine can no longer be incorporated into DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what does the incorporaton of FdUMP into DNA do

A

inhibits DNA synthesis function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what does the incorporation of FdUMP do to RNA

A

interferes with RNA processing and function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what can tumour cell resistance mechanisms include

A

decreased activation of 5FU, increased thymidylate synthase activity and reduced drug sensitivity of this enzyme

22
Q

what is folinic acid usually administered as

A

calcium or sodium folinate

23
Q

what is it an adjuvant to

A

it is an adjuvant used in cancer chemotherapy involving the drug methotrexate

24
Q

how is folinic acid administered

A

as a pill or into the vein

25
Q

what are the indications for folinic acid

A

used to diminish the toxicity and counteract the effects of impaired methotrexate elimination and of inadvertent overdosages of folic acid antagonists, and to treat megaloblastic anaemias due to folic acid deficiency
also used in combination with 5-FU to prolong survival In the palliative treatment of patients with advanced colorectal cancer. It enhances the effect of 5FU by inhibiting thymidylate synthase

26
Q

what is the mechanism of action of folinic acid

A

as leucovorin is a derivative of folic acid, it can be used to increase levels of folic acid under conditions favouring folic acid inhibition

Leucovorin enhances the action of fluorouracil by stabilising the bond of the active metabolite (5-dUMP) to the enzyme thymidylate sythetase

This is because 5-FU doesn’t stay long in the system and so folinic acid allows 5-FU to bind to this enzyme

27
Q

describe the TMN staging of colon cancer

A

T =
tumour
Goes from Tis-T4b
(Go into this in more detail)

N =
node
Goes from N0-N2

M =
Metastasis
Goes from M0-M1

28
Q

what is Duke’s staging for colorectal cancer

A

This provides a 5 year prognosis
duke’s A = 90% chance of survival
Dukes B = 66% chance of survival
Dukes C = 33% chance of survival
Dukes D = <5% chance of survivals

29
Q

what is grade I of cancer

A

tumour cells resemble normal and aren’t growing rapidly

30
Q

what is grade II of cancer

A

tumour cells dont look normal and are growing faster than normal cells

31
Q

what is grade III of cancer

A

tumour cells look abnormal and are proliferating rapidly

32
Q

cells that resemble tissue are more likely to be what

A

well differentiated

33
Q

cells that resemble stem cells tend to be waht

A

poorly differentiated

34
Q

what is the pathology of colon cancer

A

the mucosal lining of the colon contain crypts
These are the sites of mutations in colon cancer
If the mutation occurs in the differentiated villi / epithelial cells, then the development of the tissue isn’t so harmful
If the mutation occurs In the crypts then the development of the tissue is very harmful (polyps)

35
Q

what is FAP

A

this is the inherited disease of the colon which predisposes the individual to developing colorectal cancer

in this condition, hundreds of polyps line the luminal surface of the colon

this condition has a low but predictable frequency of development into colorectal cancer

36
Q

what is APC

A

APC forms part of the Wnt signalling pathwat, forms part of the intracellular protein complex

APC gene is a TSG

37
Q

what does APC encode for

A

a protein consisting of 2800 amino acids which binds to b catenin, thus causing down regulation of it by initiating its proteloytic degradation
this stops the cell from over proliferation

38
Q

what happens if there is a mutation in APC

A

Prevents the degradation of B-catenin and so results in excessive proliferation of the cell

Makes the genome unstable by affecting the spindling during mitosis

Stimulates the migration of malignant stem cells out of the crypts (polyps)
deregulation of APC/B-catenin is an obligate and early step in CRC

39
Q

what is HNPCC

A

an inherited disease of the colon that causes 2-3% of all colorectal cancers

40
Q

what is HNPCC also known as

A

lynch syndrome

41
Q

what is the features of the polyps in HNPCC

A

very few polyps form, but the progression of development into colorectal cancer is faster - 2-3 years

42
Q

what is the mismatch repair genes

A

they have a higher mutation rate than other genes

if mismatch genes are mutated then any errors in newly made DNA strands cant be repaired

43
Q

what is MLH1 gene

A

is a mismatch repair gene, associated with micro satellite stability. a mutation of this can lead to microsatellite instability and HNPCC

44
Q

how do the MLH1 mutations cause cancer

A

the cells are constantly making mistakes when making new DNA strands that aren’t being repaired
This means the mutation rate in these patients increases significantly
This means that they can acquire more mutations more easily in specific regions of the genome such as in oncogenes and TSGs
An elevated mutation rate doesn’t cause cancer; mutations in specific areas of the genome give us cancer I.e in oncogenes/TSGs

45
Q

what normally happens when TGF beta binds to its receptor

A

causes a signalling cascade to occur via Smad intracellular proteins

46
Q

what does this cause

A

This causes:
Activation of CKis - thus inhibiting proliferation
Inhibition of MYC - a pro-proliferative molecule - thus inhibiting proliferation
mutations can occur in the Smad 4 pathway, thus leading to an increase in proliferation

47
Q

mismatch repair gene mutation explanation

A

TGF-beta is a growth inhibitory factor

Mismatch repair mutations cause deletion of AA bases

This causes a truncation of the TGF-beta receptor gene, meaning that it is no longer synthesised

As a result, the cell now becomes unresponsive to anti-proliferative signals

TGF-beta receptor gene mutation occurs in 90% of colorectal cancers with a mismatch repair gene

48
Q

what is the inflammation pathway

A

thereforewithout the TGF-beta pathway, the colon become sensitised to inflammation and so can develop colorectal cancer
In response to the inflammatory response, the NF-kbeta pathway is upregulated, leading to increased gene expression
Proliferation
Anti apoptosis

49
Q

what does chronic inflammation in this manner cause

A

ulcerative colitis, which increases the risk of developing colorectal cancer

50
Q

what is angiogensis

A

damage to the vasculature leads to an increase in vascular endothelial growth factor -VEGF

this results in angiogenesis

51
Q

what can angiogenesis be treated with

A

be treated by VEGF inhibitiors e.g avastin

Semester 4 (80 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions