What is a tumour? What is cancer?

A tumour refers to the repeated mitosis of a mass of abnormal cells. A benign tumour, such as a mole, is harmless as it does not spread from its original site. A malignant tumour (aka cancer) spreads through the body and destroys other tissues.

Steps in tumour/cancer formation

  1. Mutation: Cancers start with changes (mutations) in genes that control cell division. Tumour-suppressor genes are switched off and proto-oncogenes mutate to become oncogenes.
  2. Cellular Response: Cancerous cells do not respond to signals from other cells and continue to divide.
  3. Immune System Evasion: Cancerous cells are not removed by the immune system.
  4. Rapid Mitosis: Cancer cells undergo rapid mitosis.
  5. Tumour Growth: The tumour enlarges, and cells change their characteristics.
  6. Blood Supply: The tumour gets a blood and lymph vessel supply.
  7. Metastasis: Tumour cells spread in the blood and lymph to other body parts, invading other tissues and forming secondary cancers.
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