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MOD > 8 Intro to carcinogenesis: why and how neoplasms occur > Flashcards

8 Intro to carcinogenesis: why and how neoplasms occur Flashcards

1
Q

neoplasm is a … ?

A

newly formed collection of cells resulting from abnormal cellular proliferation that persists after the initial stimulus is removed

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2
Q

Give 3 features of benign tumours
1. they are generally …
2. localised / not localised
3. …… perimeter

A
  1. self-contained
  2. localised
  3. have a well-defined
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3
Q

How do benign tumours grow from a central mass ?

A

slowly, expanding outward

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4
Q

When are benign tumors dangerous ?

A

when they compress surrounding tissues

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5
Q

What could a benign tumor near a blood vessel do ?

A

restrict the flow of blood

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6
Q

What could a benign tumor in the abdomen do ?

A

impair digestion

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7
Q

What could a benign tumor in the brain do ?

A

cause paralysis

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8
Q

malignant tumours are …
1. location ?
2. action on surrounding tissues ?
3. of adjacent cells their growth is …

A
  1. not self-contained
  2. doesn’t compress
  3. irregular invasion
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9
Q

Although malignant tumors may grow slowly what are they capable of ?

A

very rapid growth

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10
Q

What are malignant tumors NOT in location comparison to benign tumors ?

A

localised

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11
Q

Through metastasis what do malignant tumors do ?

A

they shed cells that travel through the bloodstream and infect tissues at other locations

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12
Q

What are malignant tumors capable of doing ? include a example

A

establish malignant growth in a different type of tissue e.g. breast cancer can spread to bone tissue

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13
Q

What can neoplasms be either of ?

A

benign or malignant

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14
Q

What are the characteristics of a benign neoplasm ?

A
  • well cicrumscribed (has distinct boundaries)
  • slow growing
  • non-invasive
  • closely resembles the tissue of origin
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15
Q

Give 2 examples of benign neoplasms that are medically important

A
  • uterine fibroids
  • meningioma
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16
Q

what are the most common benign tumors in women of childbearing age ?

A

uterine fibroids

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17
Q

What percentage of women are affected by uterine fibroids by age 50?

A

80-90%

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18
Q

What are some symptoms associated with uterine fibroids?

A

Pain, excessive menstrual bleeding, or infertility.

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19
Q

What is the most frequently reported primary CNS tumor?

A

Meningioma

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20
Q

What proportion of all CNS tumors do meningiomas account for?

A

Approximately 36%.

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21
Q

What are some potential complications of meningiomas despite being benign?

A

Potential neurological symptoms due to their location in the central nervous system.

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22
Q

How can uterine fibroids potentially cause infertility ?

A

by obstructing the fallopian tubes and impairing gamete transport

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23
Q

what is metastasis ?

A

the spread of cancer cells to locations distant from their original site

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24
Q

Aetiology of cancer is … ? what does this mean ?

A

multifactorial i.e. is caused by intrinsic & extrinsic factors

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25
Q

Give some examples of intrinsic factors

A
  • heredity
  • age
  • gender
  • sex
  • family history
  • genetic mutations
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26
Q

give some examples of extrinsic factors

A
  • chemicals
  • radiation
  • infections
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27
Q

what factors and access to healthcare affect cancer outcomes ?

A

socioeconomic factors and unequal access

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28
Q

Give 4 examples of some chemical carcinogenic agents

A
  • polycyclic aromatic hydrocarbons (PAHs)
  • aromatic amines
  • nitrosamines
  • asbestos (although not chemical , a naturally occuring silicate)
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29
Q

about 30% of cancer deaths is due to the 5 leading behavioural/dietary risk factors, which are… ?

A
  1. high BMI
  2. low consumption fruit/ vegetables
  3. no physical exercise
  4. smoking
  5. alcohol
30
Q

Extrinsic factors which contribute to cancer aetiology are classified into 3 groups … ?

A
  1. chemicals
  2. radiation
  3. infections
31
Q

Give an example of polycyclic aromatic hydrogcarbons (PAHs)

A

benzopyrene

32
Q

Give an example of a nitrosamine which is an industrial carcinogen used in the dye manufacturing process

A

2-napythylamine

33
Q

Malignant neoplasms caused by the nitrosamine 2-napythylamine showed that…
1. delay ?
2. risk of ?
3. specificity ?

A
  1. There is a long delay between carcinogen exposure & onset of malignancy
  2. Risk of cancer depends on the total carcinogen dose
  3. Sometimes organ specificity for particular carcinogens
34
Q
  1. most carcinogens enter the body in the form of ?
  2. before being converted to …. by ….?
  3. an example of one of these converted substances ?
A
  1. procarcinogens
  2. carcinogens, cellular machinery
  3. benzopyrene
35
Q

What is benzopyrene ?

A
  • a procarcinogen
  • one of main carcinogenic agents in cigarettes
36
Q
  1. What must benzopyrene first be oxidised by ?
  2. and further modified by …. to become …..
  3. this binds …. to DNA to form an ….. where it causes mutations
A
  1. P450-1A1
  2. other enzymes, benzopyrene diol epoxide
  3. covalently, adduct
37
Q

Inital chemical carcinogens are ?

A

mutagens

38
Q

promoter chemical carcinogens cause … ?

A

prolonged proliferation in target tissue

39
Q

What does the Ames test show ?

A

initiators are mutagens

promoters cause prolonged proliferation in target tissues

40
Q

Via what process does the mutant monoclonal collection of cells become fully malignant ?

A

progression

41
Q

What are complete carcinogens ?

A

carcinogens that act as both the initiators and promoters

42
Q

How much does ultraviolet (UV) light penetrate ?

A

not deeper than skin

43
Q

Ionising radiation =
1. any form of radiation that has the ability to ….
2. 2 examples

A
  1. remove electrons from atoms and molecules
  2. x-rays, nuclear radiation
44
Q

Nuclear radiation =
particles or …1… emitted from the nucleus during ..2…

A
  1. electromagnetic radiation
  2. radioactive decay
45
Q

what does nuclear radiation include ?

A
  • alpha particles
  • beta particles
  • gamma rays
46
Q

How does radiation cause cancer apart from the fact that radiation can damage DNA directly and indirectly ?

A
  • misrepairs by DNA repair proteins allow the mutation/ chromosomal rearrangement to persist
47
Q

By producing free radicals what can radiation do to DNA ?

A

damage it directly or indirectly

48
Q

How can radiation damage DNA indirectly ?

A
  • generate free radicals
  • produce secretable soluble factors that can affect distal non-irradiated cells
49
Q

What’s the most important type of radiation type and why ?

A

ultraviolet

we are exposed to this type of radiation daily from sunlight - increased risk of skin cancer

50
Q

main exposure to ionising radiation for most people is … ?

A

natural background radiation from radon which seeps from earth’s crust

51
Q

5 ways DNA can be damaged ?

A
  • cellular metabolism
  • replication errors
  • ionising radiation
  • ultra violet light
  • toxic chemical
52
Q

3 methods of DNA damage response ?

A
  • checkpoint activation
  • DNA repair
  • apoptosis
53
Q

Carcinogenesis is a multistep process , what are the 3 steps ?

A
  1. initiation - progenitor cell irreversible genetic mutation
  2. promotion -
  3. progression
54
Q

Initiation stage in carcinogenesis involves what?

A

irreversible genetic mutation in stem cell/progenitor cell

55
Q

promotion stage in carcinogenesis involves what?

A
  • clonal expansion of initiated cells within generalised hyperplasia
56
Q

what is outgrowth of pre-malignant tumours ?

A

papillomas

57
Q

progression stage in carcinogenesis involves what?

A

malignant conversion to invasive carcinoma

58
Q

What is there often between exposure to a carcinogen and clinically- detectable neoplasia ?

A

a long interval (latency period)

59
Q

Pre-malignant (benign) tumours that can progress to invasive, malignant carcinomas

A

Papilloma

60
Q

What are papillomas ?

A

pre-malignant (benign) tumours that can ultimately progress (following the acquisition of additional mutations) to an invasive, malignant carcinoma

61
Q

What have animal tests shown with initiators and promoters (both are chemical carcinogens) ?

A

Initiators must be given first followed by a second class of carcinogens called promoters

62
Q

what is the cell cycle a regular sequence of ?

A

growth and division that cells undergo

63
Q

What is Ames test designed to detect ?

A

whether a chemical can cause mutations in the DNA of an organism

64
Q

Ames test includes exposure of what ?

A

auxotrophic his (histidine) bacterial strains of Salmonella typhimurium to potential mutagens

65
Q

Some infections directly affect …. that control …

A

genes, cell growth

66
Q

Some infections directly affect genes that control cell growth whilst other do indirectly.

By causing ..1.. injury where the resulting ..2.. acts either as a ….3.. for any pre-existing mutations or else ..4.. new mutations from DNA ….5…

A
  1. chronic tissue
  2. regeneration
  3. promoter
  4. causes
  5. replication errors
67
Q

From HPV what are the direct carcinogens that act by doing what in infected host cells ?

A

HPV-16 & HPV-18
* sustaining cell proliferation and resistance to apoptosis

68
Q

HPV-16 and HPV-18 are strongly associated with what carcinoma ?

A

cervical

69
Q

what viral oncogenes do HPV-16 and HPV-18 express ?

A

E6 and E7

70
Q

Integration of HPV DNA into the host (human) genome allows what ?

A

transcription of 2 oncoproteins (E6 and 37)

71
Q

what’s the action of the viral oncogenes E6 and E7 ?

A

E6 inhibits numan TP53 function while E7 inhibits human RB1 (pRB) protein function

72
Q

What do proto-oncogenes encode for ?

A

a range of proteins with a range of normal functions

MOD (22 decks)

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