Carcinogenesis - Causes of Cancer (20)

Question 1

Chemicals

Answer 1

PAHs, nitrosamines

Question 2

Infectious agents

Answer 2

HPV, H.pylori

Question 3

Radiation

Answer 3

UV light, radon

Question 4

Minerals

Answer 4

Asbestos, heavy metals

Question 5

Physiological

Answer 5

Oestrogen, androgens

Question 6

Chronic inflammation

Answer 6

Free radicals and growth factors

Question 7

What tissue does Aflatoxin cause cancer in?

Answer 7

Liver

Question 8

What tissue does Alcohol cause cancer in?

Answer 8

Pharynx, larynx, oesophagus, liver

Question 9

What tissue does Asbestos cause cancer in?

Answer 9

Lung pleura

Question 10

What tissue do X-rays cause cancer in?

Answer 10

Bone marrow (leukaemia)

Question 11

What tissue do UV-light cause cancer in?

Answer 11

Skin

Question 12

What tissue does Oestrogen cause cancer in?

Answer 12

Breast

Question 13

What tissue does Tobacco smoke cause cancer in?

Answer 13

Mouth, lung, oesophagus, pancreas, kidney, bladder

Question 14

What tissue does HBV cause cancer in?

Answer 14

Liver

Question 15

What tissue does HPV cause cancer in?

Answer 15

Cervix

Question 16

Carcinogen

Answer 16

Agent that significantly increases risk of cancer

Question 17

Initiators

Answer 17

Carcinogens often genotoxic - chemically modify/damage DNA

Question 18

Promoters

Answer 18

Carcinogens that induce proliferation and DNA replication

Question 19

What is a complete carcinogen?

Answer 19

Can initiate and promote e.g. UV light

Question 20

Initiation requires

Answer 20

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

Question 21

Promotion

Answer 21

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

Question 22

Common genetic abnormalities

Answer 22

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

Question 23

DNA methylation in tumours

Answer 23

Often inactivates tumour suppressor genes

Question 24

Mutations in oncogenes

Answer 24

Base pair substitutions, amplification, translocations, inversions

Question 25

Mutations in TSGs

Answer 25

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

Question 26

Direct acting metabolic activation

Answer 26

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

Question 27

Metabolic activation - procarcinogens

Answer 27

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

Question 28

Metabolic activation of benzopyrene

Answer 28

(Pro-Carcinogen) BPDE active

Question 29

Defence against carinogenesis

Answer 29

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

Question 30

Tobacco smoke

Answer 30

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

Question 31

Alcohol is linked to which cancer?

Answer 31

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

Question 32

How does alcohol cause cancer?

Answer 32

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

Question 33

Oestrogen

Answer 33

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

Question 34

Chronic inflammation is associated with which cancers?

Answer 34

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

Question 35

How does chronic inflammation cause cancer?

Answer 35

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