Carcinogenesis - Causes of Cancer (20) Flashcards

1
Q

Chemicals

A

PAHs, nitrosamines

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2
Q

Infectious agents

A

HPV, H.pylori

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3
Q

Radiation

A

UV light, radon

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4
Q

Minerals

A

Asbestos, heavy metals

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5
Q

Physiological

A

Oestrogen, androgens

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6
Q

Chronic inflammation

A

Free radicals and growth factors

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7
Q

What tissue does Aflatoxin cause cancer in?

A

Liver

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8
Q

What tissue does Alcohol cause cancer in?

A

Pharynx, larynx, oesophagus, liver

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9
Q

What tissue does Asbestos cause cancer in?

A

Lung pleura

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10
Q

What tissue do X-rays cause cancer in?

A

Bone marrow (leukaemia)

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11
Q

What tissue do UV-light cause cancer in?

A

Skin

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12
Q

What tissue does Oestrogen cause cancer in?

A

Breast

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13
Q

What tissue does Tobacco smoke cause cancer in?

A

Mouth, lung, oesophagus, pancreas, kidney, bladder

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14
Q

What tissue does HBV cause cancer in?

A

Liver

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15
Q

What tissue does HPV cause cancer in?

A

Cervix

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16
Q

Carcinogen

A

Agent that significantly increases risk of cancer

17
Q

Initiators

A

Carcinogens often genotoxic - chemically modify/damage DNA

18
Q

Promoters

A

Carcinogens that induce proliferation and DNA replication

19
Q

What is a complete carcinogen?

A

Can initiate and promote e.g. UV light

20
Q

Initiation requires

A

Chemical modification of DNA and replication of modified DNA and mis-incorporation by DNA polymerase

21
Q

Promotion

A

Stimulate two rounds of DNA replication required for mutation fixation and stimulate clonal expansion of mutated cells

22
Q

Common genetic abnormalities

A

Base pair substitution, frameshift, deletion, gene amplification, chromosomal translocation, chromosomal inversion, aneuploidy

23
Q

DNA methylation in tumours

A

Often inactivates tumour suppressor genes

24
Q

Mutations in oncogenes

A

Base pair substitutions, amplification, translocations, inversions

25
Q

Mutations in TSGs

A

Base pair substitutions, frameshifts, deletions, insertions, chromosomal rearrangements, chromosome loss, promoter methylation

26
Q

Direct acting metabolic activation

A

Interact directly with DNA e.g. oxygen radicals, nitrosamines, UV light, ionising radiation

27
Q

Metabolic activation - procarcinogens

A

Require enzymatic (metabolic) activation before they react with DNA e.g. aromatic amines, polycyclic aromatic hydrocarbons (PAHs)

28
Q

Metabolic activation of benzopyrene

A

(Pro-Carcinogen) BPDE active

29
Q

Defence against carinogenesis

A

Exposure to myriad carcinogenic agents, many levels of defence, dietary antioxidants, detoxification mechanisms, DNA repair enzymes, Apoptotic response to unrepaired genetic damage, Immune response to infection and abnormal cells

30
Q

Tobacco smoke

A

19 carcinogens (benzopyrene, acrolein, nitrosamines, radioactive lead and polonium, cadmium, chromium), X100 increased risk of head and neck cancer

31
Q

Alcohol is linked to which cancer?

A

Oral, oesophageal, pharynx, larynx, breast bowel and liver cancer

32
Q

How does alcohol cause cancer?

A

Converted into acetaldehyde (cause DNA damage), increases levels of oestrogen and testosterone, increases uptake of carcinogenic chemicals into cells within upper GI, reduces levels of folate (accurate DNA replication), can kill surface epithelium > unscheduled proliferation

33
Q

Oestrogen

A

Stimulate cell division and induce DNA damage, binds to transcription factors (breast cancer)

34
Q

Chronic inflammation is associated with which cancers?

A

Colitis, hepatitis, Barrett’s metaplasia, gastritis, gallstones

35
Q

How does chronic inflammation cause cancer?

A

DNA damage from release of free radicals by immune cells (initiation) and growth factor induced cell division to repair tissue damage (promotion)