Photocarcinogenesis Flashcards

1
Q

What is carcinogenesis

A

The process by which a normal cell becomes a malignant cancer cell

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2
Q

What is cancer

A

An accumulation of abnormal cells that multoply through uncontrolled cell division and spread to other parts of the body by invasion and/ or distant metastasis via the blood and lymphatic system

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3
Q

What are the 3 critical steps of cancer

A

Normal cells becoming abnormal cells
Abnormal cells growing to form a tumour
Metastasis

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4
Q

What does uncontrolled cell proliferation require

A

multi step gene damage.

E.g gain of function of oncogenes (accelerator) and loss of function of tumour suppressors (brakes)

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5
Q

What are the 6 hallmarks of cancer

A
Autonomous growth signals
Insensitivity to anti-growth signals
Resist cell death (apoptosis)
Limitless potential to divide 
Angiogenesis
Invasion and metastasis
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6
Q

What can cause damage to DNA

A

Carcinogens (smoking, UV light)
Inherited defects
Natural accumulation of DNA damage (increases with age)

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7
Q

What is more harmful to humans UVB or UVA

A

UVB

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8
Q

How are dimers removed

A

by nucleotide excision repair

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9
Q

What does an accumulation of photoproducts lead to

A

Mutation
Genomic instability
Cancer

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10
Q

What can mutations in genes involved in DNA repair lead to

A

Mutator phenotype whereby cells accumulate further mutations at a greatly increased rate because of failure of DNA repair

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11
Q

What leads to chromosome instability

A

Damage to genes that control the integrity of cell division

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12
Q

What does UVA cause

A

Indirect oxidative damage

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13
Q

What does UVB cause

A

direct DNA damage

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14
Q

What 3 things happen in UV induced immunosuppression

A

Dendritic cells lose ability to present antigen
T Cells sqitch from helper to suppressor; refulatory T cell predominate
Keratinocytes and DCs secrete immunosuppressive cytokines

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15
Q

What is UVR

A

a complete carcinogen- mutagenic and immunosuppressive

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16
Q

What are 6 general risk factors for skin cancer

A
Sunlight (latitidue, sunburn in childhood, intense intermittent exposure)
Genetic susceptibility (skin type)
Chemicals  (drugs, arsenic)
Age 
Immunosuppression
HPV
17
Q

What happens to badly UV damaged keratinocytes due to sunurn

A

They undergo apoptosis or programmed cell death

18
Q

What is Naevoid basal cell carcinoma (gorlin’s syndrome)

A

Autosomal dominant familil cancer syndrome

19
Q

What is TP53 gene known as

A

The guardian of the genome

20
Q

In what conditions is there a TP53 mutation found

A

AK
Carcinoma in situ
SCC

21
Q

Collagen 7 deficiency causes what

A

blistering of the skin from birth

22
Q

Patients with Collagen 7 deficiency commonly die due to what

A

metastatic SSC

23
Q

Give some examples of phototoxic drugs

A
Voriconazole (antifungal)
Thiazide diuretics 
NSAIDs 
Anti-TNF
Azathioprine
24
Q

What type of drug may reduce the risk of SCC

A

mTOR inhibitors

25
Q

What are the 3 treatment options for the treatment of premalignancy

A

Cryotherapy
Suergy
Photodynamic therapy