5

Question 1

What are the two types of Risk with cancer?

Answer 1

1) Mutations Risk

2) Tumour Promoters Risk

Question 2

Mutations Risk

Answer 2

Permanent change in DNA sequence caused by mutagens, tobaco, UV, IR, chemo

Question 3

Tumour promoters Risk

Answer 3

Inflammation, alcohol, chemical promoters and menstruation lead to increased proliferation

Question 4

How does inflammation cause cancer?

Answer 4

• Promotes mutagenesis: ROS, RNS are produced
• Promotes tumour progression: NF-kB induces cytokines, prevent apoptosis and increases proliferation
• Promotes metastasis: activated neutrophils secrete TNF, angiogenesis and migration.
  ROS and RNS lead to oxidised bases, single and double strand breaks occur -> persistent DNA damage.

Question 5

What does change in gene expression do?

Answer 5

Change in gene expression= chronic inflammation= persistent production of ROS/RNS.

Question 6

How does smoking lead to cancer?

Answer 6

Leads to p53 (12th codon) and KRAS (triple of codons) mutations, by Benz(a)anthracene that is converted to epoxide in the lung and reacts with guanine in DNA, which is then misread as thymine during replication: transversion mutation.

Question 7

What is the main risk of smoking?

Answer 7

• 20x increased risk of lung cancer

- <60 chemicals that damage DNA

Question 8

How do bacteria lead to cancer?

Answer 8

H.pylori causes inflammation in the stomach -> ROS/RNS -> free radicals -> DNA damage; gastric carcinoma.

Question 9

How do viruses lead to cancer?

Answer 9

HPV produces oncogenic proteins E6 and E7; E6 targets p53 for degradation and E7 inhibits Rb.

Question 10

How do animals lead to cancer?

Answer 10

• Flatworms: bladder cancer and bile duct cancer
• Tapeworms cause inflammation
• Malaria: lymphoma
• Dogs and Tasmanian devils can spread cancers by contact

Question 11

How does Ionising radiation lead to cancer?

Answer 11

dislodges electrons, makes molecules reactive

• > DNA damage.
• Alpha emitters (H+ nucleus)
• Beta emitters (high energy electrons emitted from nuclei)
• Gamma radiation (high frequency electromagnetic radiation emitted from decaying nuclei)
• X-rays
• Cosmic radiation (very high energy charged particles from space)

Question 12

How does ultraviolet radiation lead to cancer?

Answer 12

lower energy; primarily from sunlight.

Causes cyclo-pyrimidine dimers and 6-4 photoproducts between adjacent pyrimidine bases.

Question 13

What environmental mutagens lead to cancer?

Answer 13

• Occupational chemicals/waste products
• Natural products (fungal toxins)
• Medical mutagens: chemotherapy drugs, radiotherapy, x-rays, herbal products (aristolochia).
• Atmospheric particles, from exhaust, e.g. PM10s= lung cancer

Question 14

How is food linked to cancer?

Answer 14

Fruit and veg are linked to lower risk of mouth, throat and lung cancer and fibres reduces bowel.
Processed and red meat increases bowel cancer risk.

Question 15

How does obesity increase cancer risk?

Answer 15

Fat cells produce proliferative signals (estrogen, androgen, insulin); inflammatory signaling and recruitment of immune cells; abdominal fat partially harmful.

Question 16

Why does physical activity reduce the risk?

Answer 16

Physical activity = decrease in insulin and estrogen + more movement through digestive system, therefore less contact with carcinogens (alcohol) + reduces inflammation and stress.

Question 17

What cancers does alcohol increase risk for?

Answer 17

Causes 4% of Cancers

Increased risk of mouth, throat, breast, liver and bowel cancers

Question 18

How does alcohol cause risk?

Answer 18

Converted to acetaldehyde which can damage DNA and causes inflammation; leads to ROS.

Can increase estrogen levels

Question 19

How does menopause age effect BC risk?

Answer 19

Later menarche decreases BC risk

Earlier menopause decreases BC risk

Question 20

Does pregnancy and breastfeeding increase or reduce risk of BC and O cancer?

Answer 20

Pregnancy reduces breast and ovarian cancer risk

Breast feeding >1 reduces breast cancer risk

Question 21

How do hormone levels increase cancer risk?

Answer 21

Increase in progesterone and estrogen leads to cancer:

• Early menarche, later menopause, no children
• Hormone replacement therapy
• Hormonal contraceptives

Question 22

Do genetics contribute to cancer risk? Give examples and why

Answer 22

BRAC1 and BRAC2 in breast cancer: x5 higher risk

Mutations in oncogenes and tumour suppressors only passed on if occur in germ cells.

Question 23

How is ‘chance’ a risk?

Answer 23

1 in 109 nucleotides =mistake in DNA replication = cancer