Carcinogenesis Flashcards
Define carcinogenesis
The transformation of normal cells to neoplastic cells through permenant genetic alterations or mutations
What cells does carcinogenesis apply to
Malignant neoplasms
Define oncogenesis
Benign and malignant tumours
How many steps are in carcinogenic
Several
What do carcinogens result in
Cancer
What do oncogens reuslt in
Tumours
What is the biggest cause of cancer
Environmental factors (85%)
What are three complications with trying to identify carcinogens and risk of cancer
- Can be decades to develop
- Complexity of the environment
- Ethical constraints
Where is hepatocellular carcinoma common
AREAS with high hepatitis B/C and mycotoxins (Egypt)
Is hepatocellular carcinoma common in UK and USA
No
Where is oesophageal carcinoma common
Japan, China (chicken), Turkey and Iran (extremely hot coffee - repeated exposure to heat )
What factor increases risk of oesophageal cancer
Food (Linhsien chickens)
How many deaths per year is attributed to Lung Cancer
35,000 per year
What factor is associated with lung cancer
Smoking
What other cancer is strongly related to smoking other than lung
Bladder
Where is risk of bladder cancer increased
Those who work in the aniline dye and rubber industries
What is the causative agent of bladder cancer
Beta-nephthylamine
Where was scortal carcinoma at its peak risk
Chimney sweeping
What was the carcinogen involved in scrotal cancer with chimney sweeps
Polycyclic aromatic hydrocarbons
How did chernobyl contribute to an increase in cancer incidence in Ukranian children
Release of I(125) and I(131) into the atmosphere
Moved into ukraine and gave children thyroid cancer 4 years later
Name some methods of experimental evidence for cancer causes (3)
- Incidence of tumours in lab animals
- Cell/tissue cultures
- Mutagenicity testing in bacterial cultures
Why is experimental evidence on animals NOT an effective way to prove cancer
- Animals/cultures may metabolise agents differently to humans
- Bacterial mutation may not = carcinogenicity in bacteria but may do in humans
What are 5 classes of carcinogen
- Chemical
- Viral
- Ionising and non-ionising radiation
- Hormones, parasites and mycotoxins
- Miscellaneous
How do chemical carcinogens act on tissues
- Directly
- Convert from pro-carcinogens -> ultimate carcinogens
- Enzymes required may be ubiquitous or confined to certain organs
What tumours can polycyclic aromatic hydrocarbons cause
Lung and Skin cancer
What are the source of polycyclic aromatic hydrocarbons
Smoking
Mineral Oils
What cancer can aromatic amines cause
Bladder cancer
Source of aromatic amines
Rubber/dye workers
What can nitrosamines cause
Gut Cancer
What cancer can alkylating agents cause
Leukaemia
What complications can arise from exposure to UV light
Increase in BCC, melanoma and SCC
Increase in Xeroderma
Pigmentosum
In what job are skin cancers common
Radiographers
What career has an increased risk of lung cancer
Uranium miners
An increase in what hormone increases the chance of which cancer
- Oestrogen
2. Hepatocellular carcinoma
What mycotoxin increases the risk of cancer and what cancer is this
- Alfatoxin B1
Hepatocellular carcinoma
What parasite increases the chance of bladder cancer
Shistosoma
What parasite causes cholangiocarcinoma
Chlonorchis Sinensis
What cancer is caused by Asbestos
Malignant mesothelioma
Lung cancer
Asbestosis
What is malignant mesothelioma
Cancer of mesothelium
What five host factors can result in a cancer
- race
- diet
- constitutional factors (age, gender)
- Premalignant lesions
- Transplacental exposure
What cancer is common in India and SE asia and why
Increased oral cancer
Due to reverse smoking and metal chewing
Why is skin cancer risk lower in blacks
Due to melanin
Give three examples of constitutional host factors
- Inherited predisposition
- Age
- Gender
What chromosome causes increased predisposition for familial polyposis coli
Chromosome 5
What chromosome causes increased predisposition for retinoblastoma
Chromosome 13
How is age associated with cancer
Increases with age
How is gender associated with cancer
e.g. Breast cancer in females
What are premalignant lesions
An identifiable local abnormality that is associated with an increased risk of a malignant tumour developing at the site
4 examples of premalignant lesions
- Colonic polyps
- Cervical dysplasia
- Ulcerative colitis
- Undescended testis
How did diethylstilbestrol effect women who wanted to stop abortions
Increased risk of transplacental carcinogenesis
