carcinogenesis Flashcards
what is carcinogenesis?
The transformation of normal cells to neoplastic cells though permanent genetic alterations or mutations
- a multistep process
what are carcinogens ?
Agents known or suspected to cause tumours
describe the term carcinogenic
cancer causing
describe the term oncogenic
tumour causing
what in the environment may cause cancer?
85% of cancer is risk is environmental
PROBLEMS
Latent interval may last decades
Complexity of environment
Ethical constraints
occupation/behavioural risks- lung cancer
strong association with smoking
occupation/behavioural risks- bladder cancer
increased incidence in aniline dye and rubber
occupation/behavioural risks- scrotal cancer
increased incidence in chimney sweeps
where is Hepatocellular carcinoma common/uncommon?
-Uncommon in UK/USA
-Common in areas with ↑ Hepatitis B/C and mycotoxins
where is oesophageal carcinoma common/uncommon?
↑↑ incidence in Japan, China, Turkey and Iran
? Dietary factors (Linhsien chickens)
what are the classes of carcinogens
- chemical
- viral
-ionising and non ionising radiation
-hormones, parasites and mycotoxins
-miscellaneous
classes of carcinogens- chemical
No common structural features
Some act directly
Most require metabolic conversation from pro-carcinogens to ultimate carcinogens
Enzyme required may be ubiquitous or confined to certain organs
classes of carcinogens- ionising and non ionising radiation
Exposure to UVA or UVB
Ionising radiation
Long term effect
Skin cancer in radiographers
Lung cancer in uranium miners
Thyroid cancer in Ukrainian children
what are host factors?
things you can’t change
name 5 host factors
- race
-diet - constitutional factors- age, gender
- premalignant conditions
-transplacental exposure
host factors- race
Decreased skin cancer in black people (melanin)
Increased oral cancer in India, SE Asia (reverse smoking)
host factors- constitutional factors
Inherited disposition
Age – incidence increases with age
Gender – breast cancer F:M = 200 (more common in women)
host factors- premalignant conditions
Identifiable local abnormality associated with increased risk of malignancy at that site e.g. colonic polyps, undescended testis, cervical dysplasia
