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Dermatology > Photocarcinogenesis > Flashcards

Flashcards in Photocarcinogenesis Deck (14)
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1
Q

What is the definition of cancer?

A

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

2
Q

What are the hallmarks of cancer?

A
Sustaining proliferative signalling 
Evading growth suppressors
Activating invasion and metastasis 
Enabling replicating immortality 
Inducing angiogenesis 
Resisting cell death
3
Q

What are the emerging hallmarks and enabling characteristics of cancer?

A

Avoiding immune destruction
Tumour promoting inflammation
Genome instability and mutation
Deregulating cellular energetics

4
Q

What is an oncogene?

A

Over active form of a gene that positively regulates cell division
Drives tumour formation when activity or copy number is increased e.g. Ras, raf or growth factor receptors

5
Q

What is a tumour suppressor gene?

A

Inactive or non functional form of a gene that negatively regulate cell division - Rb, p53

6
Q

What is important to understand in sun exposure in relation to risk of skin cancer?

A

Dose and pattern
Latitude
Sunburn in childhood
Intense intermittent exposure vs chronic life long UV exposure

7
Q

What type of sun exposure predisposes to SCC?

A

Life long cumulative UV exposure

8
Q

What type of sun exposure predisposes to melanomas and BCC?

A

Intermittent burning episodes of sun exposure

Sun bed use

9
Q

Exposure to which chemicals can increase the risk of NMSC?

A
Coal tar pitch 
Soot
Creoste
Petroleum products
Shale oils
Arsenic
10
Q

What type of DNA damage does UVB radiation lead to?

A
Direct DNA damage
CPDs
Pyramidine pyramidine 6-4 photo products
Repaired by NER 
CC-TT UV signature mutation
11
Q

What type of DNA damage does exposure to UVA sun do?

A

Oxidation of deoxyguanosine forming 8-oxo depxyguanosine
Repaired by base excision repair
C-A point mutation

12
Q

How does UV act in an immunosuppressive way?

A

Depletion of langerhans cells skin and reduce ability to present antigens
Generation of UV induced and regulatory T cells with immunosuppressive activity
Secretion of anti-inflammatory cytokines like IL-10

13
Q

What mutations are important in the development of BCC?

A

PTCH1 which is a key component in the hedgehog signalling pathway - this pathway induces cell proliferation and angiogenesis

14
Q

What mutations are important in melanoma?

A

Ras/raf/MAPK
Vemurafenib targets B-raf
Tramatenib targets MEK
There are familial melanomas that alter the activity of CDK4