Cancer Flashcards
what is cancer?
Rapidly abnormally growing tissue which metastasises
what is a neoplasm?
New growth - abnormal mass of tissue, the growth of which is virtually autonomous and exceeds that of normal tissues. The growth is uncoordinated and persists after the cessation of the stimuli that initiated the change.
What is a carcinogen?
Has potential to cause cancer
How are tumours named?
Benign tumours end in -oma
Malignant tumours end in:
carcinoma - parenchyma
sarcoma - stromal
What is parenchyma and what is stroma?
parenchyma - functional tissue of an organ
stroma - tissue with connective or structural role e.g. vessels, connective tissue, blood cells
What are the four differences between benign and malignant tumours?
- Differences in differentiation
Malignant tumours show anaplasia (no differentiation)
Benign tumour cells are relatively well differentiated - Rate of Growth
Benign tumour are slower growing than malignant tumours - Local Invasion
Benign tumours don’t tend to infiltrate the basal lamina - Metastasis
Benign tumours don’t metastasise
What are the mechanisms of invasion/metastasis?
- lymphatics
- haematogenous
- body cavities
- contiguous - shares a common border so touching
Which route to carcinomas commonly follow?
lymphatics
Which route do sarcomas usually follow?
haematogenous
Why do tumours use veins rather than arteries to spread?
The walls are thinner
What are the most common cancers in men and women?
women: breast, lung, colon/rectum
men: prostate, lung and colon/rectum
How does geography affect the epidemiology of cancer?
- Stomach cancer higher in Japan compared to the USA
- Colon cancer much less in Japan
- Melanoma much more common in NZ and Australia
- Hepatocellular Carcinoma more common in Uganda due to aflatoxin
- High incidence of oesophageal cancer in China and Iran due to nitrates in soil and abrasives in diet
What are some examples of how genetics can lead to cancers?
Autosomal dominant inherited cancer syndrome:
retinoblastoma, FAP
Recessive:
Xeroderma Pigmentosum - increases susceptibility to skin cancers
Familial Cancer Syndromes:
Multiple Endocrine Neoplasia (MEN)
What percentage of cancers have hereditary origin?
10%
What is carcinogenesis?
- Involves multiple mutations over a period of time
- Malignancy is acquired in a step-wise fashion - tumour progression
- The non-lethal changes in the cell are the driving force of carcinogenesis
What are the 4 types of regulatory genes?
- oncogenes
- TSG
- pro-apoptotic/anti-apoptotic genes
- DNA repair genes
What are the main classes of carcinogens?
- chemicals
- viruses
- radiation
- hormones
- bacteria, fungi and parasites
- miscellaneous
What are chemical carcinogens?
- No common structural features
- Some need metabolic conversion from inactive procarcinogen to an active ultimate carcinogen while others don’t
- If appropriate enzyme is present within the skin, tumour occurs at the site
What are the major classes of chemical carcinogens?
Hydrocarbons Amines Nitrosamines Azo dyes Alkylating agents
Who are affected by oncogenic viruses and give examples?
- Generally affect the young and immunosuppressed
- HPV: cervical cancer
- HBV: hepatocellular carcinoma
- EBV: Burkitt’s lymphoma
What are some DNA/RNA oncongenic viruses, and bacterial carcinogens?
DNA - HPV, EBV, HBV
RNA - HTLV1: causes leukaemia
Bacterial - H.pylori (gastric carcinoma)
Which cancers does radiation cause?
Ultraviolet - BC(basal cell carcinoma), SCC (squamous cell carcinoma) and MM
Ionising Electromagnetic Radiation - causes increase in leukaemia and solid tumours
What are the clinical effects of tumours?
- anxiety
- pressure, ulceration, infection and bleeding
- metabolic cancer cachexia (reduced fat and muscle)
- paraneoplastic syndrome (consequences of cancer e.g. by immune system or cell secretion) for example neuropathies
What are some tumours associated with oncogenes?
- Brukitt’s lymphoma
- Neuroblastoma
