L: Neoplasia 3

Question 1

Define carcinogenesis?

Answer 1

Initiator of cancer formation

Question 2

What are the different categories of carcingogens?

Answer 2

Intrinsic
- Hereditary 
- Age 
- Sex (particularly hormones)
Extrinsic
- Environment 
--> Chemicals 
--> Radiation 
--> Infection 
- Behaviour

Question 3

What are some of the behavioural carcinogens?

Answer 3

High BMI
Low fruit and vegetable intake
Lack of physical activity 
Tobacco use --> 25% of all deaths from cancer
Alcohol 
Sun exposure

Question 4

What does smoking increase the risk of?

Answer 4

Biggest preventable cause of cancer
Lung cancer 7/10 develop
Mouth 
Pharaynx
Nose and sinus
Larynx
Oesophagus 
Liver
Pancreas
Stomach 
Kidney 
Bowel 
Ovary 
Bladder
Cervix 
Some types of leukaemia

Question 5

What is one of the biggest indicators of the causes of cancers?

Answer 5

Look at migrating populations
Compare baseline risk in home country
Change in risk after settled in new geographic location
Approximately 85% cancer due to environmental risk factors
e.g. Japanese men lung cancer risk 75% risk in Japan move to Hawaii risk reduced to 15%–> environmental component

Question 6

What have chemicals shown us about carcinogenesis?

Answer 6

Chemical 2-naothylamine industrial chemical used to dye clothes
Causes malignant neoplasms
Showed
1- Delay between carcinogen exposure and malignant neoplasm onset
2- Risk of cancer depends on total carcinogen dosage
3- Sometimes organ specificity for particular carcinogens

Question 7

How do chemical carcinogens work?

Answer 7

Initiator needed to make the mutation–> sufficient dose needed
Followed by prolonged exposure to a promoter

Question 8

How do we work out what chemicals will go on to cause mutations and act as carcinogens?

Answer 8

Ames test
Tells you what chemical maybe an initiator and what maybe a promoter
Salmonella stain and rat extract–> add potential mutagen compare control plate and test plate
Grow the culture
See if the mutagen is an initiator and if it is carcinogenic
Carcinogens that are both initiators and promoters are called–> complete carcinogens

Question 9

What do initiators have to cause?

Answer 9

Non lethal genetic damage

Lethal genetic damage will cause the cell to die and be apoptosed

Question 10

What are the different types of chemical carcinogens?

Answer 10

Polycyclin aromatic hydrocarbons
Aromatic hydrocarbons
N-nitroso compounds
Alkylating agents 
Natural products --> asbestos 
Some are pro-carcinogens--> converted to carcinogens by cytochrome p450 enzymes in liver