Session 10 - Neoplasia 3 Flashcards
Give some examples of intrinsic host factors which influence neoplasms formation
- Age
- Gender
- Hereditary factors
Generally speaking, why does the risk of cancer increase with age?
-The longer the lifespan the greater the chance of mutation occuring
What are the two groups of extrinsic factors which influence neoplasms formation?
- Environment
- Behaviour
What are the 5 leading dietary and behavioural risks?
- High body mass index
- Low fruit and vegetable intake
- Lack of physical activity (independant from high BMI)
- Tobacco use
- Alcohol use
Do intrinsic factors or extrinsic factors have the most influence of neoplasm formation?
-Extrinsic factors
What are the three categories of extrinsic carcinogens?
- Chemicals
- Radiation
- Infection
What 3 characteristics did 2-napthylamine show about carcinogenesis?
1) There is a long delay between carcinogen exposure and malignant neoplasm onset (sometimes decades)
2) The risk of cancer depends on total carcinogen dosage
3) There is sometimes organ specificity for particular carcinogens
Why does 2-napthylamine effect the bladder?
-The dye is excreted via urine and thus becomes concentrated in the bladder
Name some industrial causes of neoplasms
- Asbestos
- Coal tars/dust
- Vinyl chloride
What is pneumoconiosis?
-Any fibrotic lung disease caused by an occupation
What is asbestosis?
-Pneumoconiosis (fibrous lung disease) caused by the inhalation of asbestos fibres (white and blue)
What is asbestos?
- Naturally occuring, thick fibres of silicate which is mined and predominantly used for insulation
- Two types white and blue (blue is worse as harder to eliminate from body as stiffer)
What is an initator?
-Anything which induces a mutation in a cell (a mutagen)
What is a promotor?
-Anything which causes prolonged proliferation in target tissues
What is the end result of initiation and promotion?
-Monoclonal expanded population of mutant cells
Through what process does a monoclonal mutant population become fully malignant?
-Progression
What are the classifications of chemical carcinogens?
- Polycyclic aromatic hydrocarbons
- Aromatic amines
- N-nitroso compounds
- Alkylating agents
- Diverse natrual compounds eg aflatoxin and asbestos
What are pro-carcinogens?
-Chemicals which are only comverted to carcinogens by cytochrome P450 enzymes in the liver
What is a complete carcinogen?
-Carcinogen that acts as both an initiator and a promotor
Provide an example of a complete carcinogen
-Smoking
What four types of ionising radiation are significant in neoplasia?
- UV
- Xrays
- Gamma rays
- Nuclear radiation (a and b particles)
Where is UV penetration limited to?
-Cannot go deeper than the skin
In what two ways does radiation damage DNA?
- Directly damages DNA bases and causes DNA breaks
- Indirectly through free radicals
What is the main exposure to ionising radiation in most people?
-Natural background radiation from radon which seeps from the earths crust
Is UV ionising radiation?
-No, it is electromagnetic radiation