AQA A Level Biology

Revision Notes

8.2.10 Two Types of Tumours

The Characteristics of Benign & Malignant Tumours

  • Tumours are groups of abnormal cells that form lumps or growths
  • They can start in any of the cells in our bodies
  • Tumours have different characteristics depending on whether they are cancerous (malignant) or non-cancerous (benign)
  • All tumours may cause harm to the body by:
    • Damaging the organ in which the tumour is located
    • Causing blockages or obstructions
    • Damaging other organs by exerting pressure

Malignant tumours

  • Malignant tumours are cancerous
  • Malignant tumours cause cancer by growing rapidly, then invading and destroying surrounding tissues
  • Cells within malignant tumours secret chemicals that cause the formation of blood vessels to supply the tumour with nutrients, growth factors and oxygen
  • Cells can break off these tumours and spread to other parts of the body through the bloodstream or lymphatic system, this is called metastasis
  • Metastasis causes the spread of tumours to other places in the body, affecting multiple organs
  • When removed through surgery, malignant tumours can still grow back
  • The formation of malignant tumours can be initiated by carcinogens such as:
    • UV or X-ray exposure
    • Tobacco from cigarettes
    • Asbestos
    • Processed meat

Benign tumours

  • Benign tumours are not cancerous
  • These tumours grow slowly 
  • Benign tumours do not invade other tissues and do not metastasise, unlike malignant tumours
  • These tumours can cause damage such as blockages or by exerting pressure on the organ it is growing in or those surrounding it
  • When removed, benign tumours do not usually grow back
  • The formation of benign tumours can be initiated by:
    • Inflammation or infection
    • Injury
    • Diet
    • Genetics
    • Toxins and radiation
  • Examples of benign tumours are:
    • Polyps found in the nose, colon and ovaries
    • Non-cancerous brain tumours
    • Warts, caused by a viral infection

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While studying Biochemistry at Oxford University, Amelia started her own tutoring service, helping to connect Science tutors with students in her local area. Amelia has experience teaching the sciences and Maths at all levels to UK and international students and, as well as being our Biology Lead, designs revision resources for Chemistry.
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