Photocarcinogenesis

Question 1

What is carcinogenesis

Answer 1

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

Question 2

What is cancer

Answer 2

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

Question 3

What are the 3 critical steps of cancer

Answer 3

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

Question 4

What does uncontrolled cell proliferation require

Answer 4

multi step gene damage.

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

Question 5

What are the 6 hallmarks of cancer

Answer 5

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

Question 6

What can cause damage to DNA

Answer 6

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

Question 7

What is more harmful to humans UVB or UVA

Answer 7

UVB

Question 8

How are dimers removed

Answer 8

by nucleotide excision repair

Question 9

What does an accumulation of photoproducts lead to

Answer 9

Mutation
Genomic instability
Cancer

Question 10

What can mutations in genes involved in DNA repair lead to

Answer 10

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

Question 11

What leads to chromosome instability

Answer 11

Damage to genes that control the integrity of cell division

Question 12

What does UVA cause

Answer 12

Indirect oxidative damage

Question 13

What does UVB cause

Answer 13

direct DNA damage

Question 14

What 3 things happen in UV induced immunosuppression

Answer 14

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

Question 15

What is UVR

Answer 15

a complete carcinogen- mutagenic and immunosuppressive

Question 16

What are 6 general risk factors for skin cancer

Answer 16

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

Question 17

What happens to badly UV damaged keratinocytes due to sunurn

Answer 17

They undergo apoptosis or programmed cell death

Question 18

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

Answer 18

Autosomal dominant familil cancer syndrome

Question 19

What is TP53 gene known as

Answer 19

The guardian of the genome

Question 20

In what conditions is there a TP53 mutation found

Answer 20

AK
Carcinoma in situ
SCC

Question 21

Collagen 7 deficiency causes what

Answer 21

blistering of the skin from birth

Question 22

Patients with Collagen 7 deficiency commonly die due to what

Answer 22

metastatic SSC

Question 23

Give some examples of phototoxic drugs

Answer 23

Voriconazole (antifungal)
Thiazide diuretics 
NSAIDs 
Anti-TNF
Azathioprine

Question 24

What type of drug may reduce the risk of SCC

Answer 24

mTOR inhibitors

Question 25

What are the 3 treatment options for the treatment of premalignancy

Answer 25

Cryotherapy
Suergy
Photodynamic therapy