Epidemiology and Incidence of Cancer Flashcards
Define: Genetic aberration
Abnormal/irregular portion of chromosomal DNA
What are the function of oncogenes?
Signal proliferation of cell cycles
Their over expression is associated with uncontrolled cell growth
What are the function of TSGs?
They code for inhibitory proteins.
Loss of function causes uncontrolled tumour growth
p53 (TSG) known as the “guardian of the genome”
Which UV light spectrum are we less concerned with?
UV-C because its blocked out by the ozone layer
[280 – 100 nm]
Causes of UV-B [320 – 280 nm] ?
- Sunburn :/
- Directly damages DNA bases: causes formation of
cyclobutane pyrimidine dimer (CPD)
CPD contains 2 thymine bases linked by strong covalent bonds. This disrupts the DNA strand and makes it difficult to read by DNA polymerase –> SKIN CANCER
This mutation causes:
- 8% malignant melanoma
- Mostly produces melanin (causes a TAN)
Causes of UV-A [400 – 320 nm] ?
Contributes to skin cancer through free radical formation - does not cause sunburn
What do UV-A and UV-B light produce?
Free radicals !
Free radicals are:
- Linked with ageing
- Cause indirect DNA damage (92% malignant melanoma)
Which type of cancer is radon gas associated with?
Lung cancer.
uranium miners most at risk because radon gas is a daughter product of radioactive decay of uranium in Earth’s crust
Three types of ionising radiation that causes cancer
- Excessive background radiation
- Excessive diagnostic radiology exposure
- Therapeutic radiation
Define: Ionisation
When an atom or molecule gains a positive or negative charge by gaining or losing electrons
Radiation-induced cancer Mechanisms
Energy deposited in biological material can produce ionisations in:
- Target molecules e.g. DNA
- interaction with water molecules to produce free radicals. These free radicals cause damage to DNA
DNA damage includes: Base damage, single-strand breaks (SSBs), double-strand breaks (DSBs)
Genomic instability
Identify the 2 modifiers to risk of radiation-induced cancer
Age: increased risk associated with exposure during childhood
Genetic susceptibility: Those with specified hereditable gene mutations
Name at least 2 cancers that can develop from this virus: Epstein-Barr Virus [EBV]
Burkitt lymphoma
Hodgkin lymphoma
Post-transplant lymphoma
Nasopharyngeal carcinoma
Human Papilloma Virus [HPV] can lead to what type of cancer?
Cervical cancer
What type of virus is HPV?
DNA virus affecting the epidermis or mucous membranes of humans
