Aetiology

Question 1

Give some examples of inherited causes of cancer

Answer 1

• Mutations in tumour suppressor genes
  
  • BRCA1 and BRCA 2 =breast and ovarian cancer
  • von-Hippel Lindau syndrome
    
    • tumours arising in multiple organs
  • p53 mutation important in almost all cancers =identidied in Li-Fraumeni syndrome
• adenomatous polyposis coli mutation = colorectal cancer

Question 2

Give some examles of chemical that act as carcinogens?

Answer 2

• Cigarette smoke
  
  • cause specific mutations in the p53 tumour supressor gene
• Aromatic amines
  
  • associated with bladder cancer
• Benzene
  
  • leukaemia
• Wood dust
  
  • nasal adenocarcinoma
• Vinyl chloride
  
  • angiosarcomas

Question 3

What are some examples of physical factors which increase the risk of cancer?

Answer 3

• radiation: UV light, imaging
• Accumulation of radioactive isotope

Question 4

What are the dietary factors which increase the risk of cancer?

Answer 4

• Low fibre diet associated with colorectal carcinomas
• Smoked food in Japan associated with Gastric carcinomas

Question 5

Give some examples of drugs which increase the risk of cancer?

Answer 5

• Cytotoxic drugs (dose dependent)
• Topoisomerase inhibitors can lead to leukaemia

Question 6

What infective agents are associated with cancer? Which cancer?

Answer 6

• Human papilloma virus (HPV) = cervical and anal cancers
• Epstein Barr Virus = non-Hodgkin’s lymphoma (NHL) and other lymohomas
• Hep B = Hepatocellular cancer
• H. pylori = Mucosal associated lymphoid tissue (MALT) tumours
• Retrovirus = T-cell lymphomas

Question 7

How are immune deficiencies implicated in the risk for cancer?

Answer 7

Increasing evidenct that the immune system is involved in tumour surveillance. Increased risk are people:

• Taking drugs that cause immunodeficiency
• Infections that damage the immune systme e.g. HIV
• congenital abnormalities of immune system i.e. T cell deficiencies