L02 - Cancer & Environmental Factors

Question 1

List 7 environmental factors that contribute to cancer.

Answer 1

1 - Diet

2 - Tobacco

3 - Alcohol

4 - Infectious disease such as HPV

5 - Indoor & outdoor pollution

6 - Water contaminants

7 - UV radiation

Question 2

List 6 substances which contribute to air pollution.

Answer 2

1 - Particulate matter of 10 and 2.5 micrometers in diameter

2 - Nitrogen dioxide

3 - Sulphur dioxide

4 - Ozone gas

5 - Carbon monoxide

6 - Polycyclic aromatic hydrocarbons (PAHs)

Question 3

What 3 aspects must be considered in a risk assessment of carcinogens?

Answer 3

1 - Potency - the potential for a given amount of substance to cause cancer

2 - Type of exposure - acute vs long term & avoidable or non-avoidable

3 - Dose response - what happens as exposure level increases or decreases

Question 4

List 6 cellular effects induced by exposure to particulate matter.

Answer 4

1 - Sustained proliferative signalling

2 - Cell death resistance

3 - Angiogenesis induction

4 - Activation of invasion and metastasis

5 - Inflammation

6 - Genome instability

Question 5

What is a DNA adduct?

Answer 5

A segment of DNA covalently bound to a cancer-causing chemical

Question 6

Describe the 3 pathways by which smoking can cause cancer.

Answer 6

1 - Nicotine and tobacco carcinogens bind to receptors that trigger AKT and PKA pathways, increasing angiogenesis and decreasing apoptosis

2 - Tobacco carcinogens cause DNA adducts, causing mutations

3 - Co-carcinogens of tobacco carcinogens trigger the PKC and AP1 pathways, enhancing carcinogenicity

Question 7

What is a co-carcinogen?

Answer 7

A substance that promotes the effects of a carcinogen in the production of cancer

Question 8

What are the IARC carcinogen classifications of processed meat and red meat?

Answer 8

Processed meat - Group 1 (“carcinogenic to humans”)

Red meat - Group 2A (“probably carcinogenic to humans”)

Question 9

List 2 anti-carcinogenic foods & their components.

Answer 9

1 - Fibre (non-starch polysaccharide)

2 - Fruit & veg - fibre, folate, vitamins C & E, flavonoids

Question 10

List 5 reasons for the link between obesity and cancer progression.

Answer 10

1 - Cholesterol metabolites induce epithelial-to-mesenchymal transition & enhance metastatic proficiency

2 - Obesity increases inflammasome activation in tumour-infiltrating myeloid cells, which drives increased IL-1 beta signalling

3 - Adipocytes express VEGF-A in response to IL-1 beta, increasing tumour angiogenesis.

4 - Obesity increases myofibroblast content, which stiffens extracellular matrices and enhances cancer cell growth.

5 - Obesity causes an increase in monocyte expression of GM-CSF, promoting neutrophil expansion. Neutrophils then accumulate in the lung and promote growth of disseminated cancer cells.

Question 11

What are crown-like structures?

Answer 11

• Dead adipocytes surrounded by macrophages

- A hallmark of the proinflammatory response

Question 12

List 7 outcomes of chronic alcohol consumption that are linked to an increased cancer risk.

Answer 12

1 - Production of acetaldehyde

2 - Induction of oxidative stress & conversion of procarcinogens to carcinogens

3 - Induction of DNA hypomethylation by depletion of SAMe

4 - Induction of Gi proteins & Erk-MAPK signalling

5 - Accumulation of iron & associated oxidative stress

6 - Inactivation of BRCA1 & increased oestrogen responsiveness (in breast)

7 - Impairment of retinoic acid metabolism

Question 13

Which condition is caused almost exclusively by exposure to asbestos?

Answer 13

Pleural mesothelioma

Question 14

List 7 lifestyle modifications in cancer prevention.

Answer 14

1 - Quit smoking

2 - Avoid sunlight

3 - Clean water supply

4 - Chemoprevention

5 - Anticancer vaccines

6 - Healthy diet

7 - Exercise