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Pathological processes > How and why neoplasms occur > Flashcards

How and why neoplasms occur Flashcards

1
Q

What are the 5 leading extrinsic risk factors for neoplasms?

A
  • high BMI
  • low fruit and veg
  • lack of exercise
  • tobbaco use
  • alcohol use
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2
Q

What are the intrinsic risk factors for neoplasms?

A
  • age
  • sex
  • hereditary
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3
Q

What are the 3 categories of extrinsic risk factors for neoplasms?

A
  • chemicals
  • radiation
  • infections
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4
Q

does intrinic or extrinsic factors have a bigger effect on cancer risk?

A

85% extrinsic

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5
Q

Which chemical is well known to be linked with bladder carinoma?

A

2- napthylamine from dye manufacturing

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6
Q

What 4 principles about chemical carcinogens does 2- napthylamine illustrate?

A
  • long delay between exposure and malignant neoplasm onset
  • risk of cancer depends on total carcinogen dose
  • sometimes organ specificity for specific carcinogens
  • chemical carcinogenesis involves initiation and promotion
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7
Q

state some industrial carcinogens which have an effect on relevant workers?

A
  • asbestos
  • coal tars
  • vinyl chloride
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8
Q

What malignancies does asbestos lead to?

A

mesothelioma

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9
Q

What is the two hit hypothesis?

A

That both tumour suppressor gene alleles are needed to be mutated in order to cause a neoplasm

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10
Q

What is the significance of the two hit hypothesis with regard to familial cancers?

A

in familial cancers the first hit is delivered from the germ line so all cells have one allele of the tumour suppressor gene which is faulty. this means they only need one more mutation for initiation of the neoplasm

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11
Q

Name some chemical carcinogens

A

polycyclic aromatic hydrocarbons, aromatic amines, N- nitroso compounds, alkylating agents

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12
Q

name and describe the test which shows that initiators are muatgens while promotors cause proliferation

A
  • ames test
  • salmonella which requires histidine and rat liver extract in tubes
  • to one tube add mutagens and then culture on agar without histidine
  • on other dont add mutagens
  • on mutagen and no histidine salmonella agar lots grow as mutate to not need histidine
  • on agar with no mutagens few or no colonies grow as lower rate of mutations
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13
Q

What is a procarcinogen and a complete carcinogen?

A

a procarcinogen is only carcinogenic when metabolised by CYP450 in liver
a complete carcinogen is both an initiator and a promotor

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14
Q

What radiation can cause mutations?

A

UV light (skin only)
X rays
a, b and y rays

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15
Q

How can radiation damage DNA?

A
  • direct damage (alters bases, single/ ds breaks)

- indirect damage (create free radials)

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16
Q

By what general mechanisms can infections be carcinogenic?

A
  • directly: mutate/ affect genes which control cell growth
  • indirectly: cause chronic injury, regeneration causes new DNA mutations due to arise due to replication errors and also act as promotors for preexisting mutations
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17
Q

How does HPV lead to increased risk of cervical cancer?

A

it expresses E6 +E7 - E6 inhibits P53 which interferes with retinoblastoma protein- both of which are tumour supressor genes - prevents apoptosis. Basically hijacks the cell cycle

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18
Q

How do hep B and C lead to increased risk of hepatocellular carcinoma?

A

cause liver cirrhois

lead to chronic inflammation and regeneration which increases risk of mutation and is also a promotor

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19
Q

How does HIV lead to cancer and what type?

A

lowers immunity so more suseptible to human herpres virus 8 which leads to kasopsis sarcoma

20
Q

How many protoonco alleles need to be mutated to cause initiation?

21
Q

How does RAS mutation lead to cancer?

A
  • RAS is G protein (proto-oncogene) which is needed to activate cyclin D and so cause cell cycle to pass restriction point
  • RAS becomes mutated so GTP always binds to it so its always active
  • cell now looses control of when it is allowed to divide
    RAS is therefor a protooncogene
22
Q

How does mutation of retinoblastoma protein lead to cancer?

A

it inhibits passage through the restriction point.
therefore when it is mutated its not expressed and so cell can go through cell cycle without inhibition.
RB is therefore a tumour supressor gene

23
Q

give examples of other things that can be coded for by proto- oncogenes and the 2 important examples we need to know

A
  • growth factor receptors (HER2)
  • transcription factors (c- MYC)
  • signal transducers (RAS)
  • growth factors
  • cell regulators (eg Cyclin)
  • apoptosis regulators (BCL2)
24
Q

Other than retinoblastoma protein, what is the other tumour surpressor gene we need to know about?

25
What is a caretaker gene?
genes that maintain the genetic stability of a cell- they're a type of tumour supressor gene that prevent accumulation of DNA damage.
26
What familial caretaker gene mutation generally leads to xeroderma pigmentosum (auto ressesive condition which causes many skin cancers at a young age) and how does this occur?
- mutation of one of the nucleotide excision repair genes - cells more suseptible to UV damage - more melanoma
27
What is the inheritance pattern of hereditary non- polyposis colon cancer (HNPCC) and what genes are mutated?
- genes that help with mismatch repair - leads to microsatallite instability - autosomal dominant
28
What genes are mutated in familial (but also sporadic) breast carinoma, how does this affect genetic stability?
- BRAC1 and 2 - they repair double strand breaks - leads to chromosomal instability - damaged DNA not repaired, massively increases risk of cancer
29
What are the 6 hall marks of cancer
1) self sufficiency in growth signals (oncogenes) 2)resistance to growth stopping signals (TSG's) 3) no limit on number of times a cell can divide (cell immortalisation) 4) sustained ability for angiogenesis 5) resistance to apoptosis 6) ability to invade and produce metastases genetic instability is an enabling characteristic
30
Why do you need promotion?
Because signals from other cells (contact inhibition) and within the cell will try to stop its dividing if there is no promotion
31
Why are most germline mutation tumour suppressor genes not protoconco genes?
Proto onco genes are dominant so if you have a defect in it, your embryological development will be incorrect and you will not survive. You need both tumour suppressor genes to be defective for uncontrolled proliferation of a cell
32
Give an example of a gene which can help the cell evade cell growth stop signals
Cyclin dependant kinase inhibitors
33
Which gene is mutated to induce angiogenesis
VEGF
34
Why do you need to activate telomerase in a cancer cell?
Because lots of cells are lost through the processes of promotion, progression, necrosis, apoptosis ect
35
Name an initiator and a promoter found in cigarette smoke
Initiator- acetaldehyde can cause mutations | Promoter - smoke is hot and so will cause inflammation and promote proliferation
36
What are the types of lung cancer?
small cell carinoma (12%) | non small cell carcinoma- adenoma, aquamous cell carcinoma, large cell carinoma
37
What is unique about a small cell carcinoma?
it often releases ADH, and sometimes ACTH
38
What types of cancer can you get in the bladder?
transition or squamous cell carcinoma
39
What is the macroscopic difference between melanoma, basal cell carcinoma and squamous cell carcinoma
basal cell a raised lump with round edges, often waxy and well circumscribed squamous cell has poorly defined edges, bleeding, everted edges melanoma is a mole changing in size, pigmentation, bleeding, itching ect
40
Do basal cell carcinomas often metastasis?
- no almost never
41
What are predistposing factors for breast cancer
- genetics BRCA2 - late 1st pregnancy - over 50 y/o - race, ethnicitiy- white most common - overweight, low exersize
42
Where does burkitts lymphoma start?
B cells
43
How does xeroderma pigmentosum present?
sun burn dry skin many freckles before age 2
44
How is cervical carcinoma screened?
pap smear- cytology 25-50 yr olds every 3 years 50-60 every 5
45
Who is invited to a breast cancer screening and how often?
50-70 yo | every 3 years

Pathological processes (8 decks)

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