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Last Updated: Tuesday March 17 2009 16:51 GMT

What is 'malignant' and 'benign'?

Skin cancer cells

Cancer cells multiply much more quickly than healthy cells. When this happens, they can stick together to form lumps.

These are known as tumours. Cells from tumours can spread to other parts of the body and cause other tumours to grow.

When people find out they have a tumour, they have to go to the doctor to find out if it is what's known as benign or malignant.

Benign tumours:

  • These are not cancers
  • Can often be removed and mostly don't come back
  • Cells from these tumours don't spread to other parts of the body.

Malignant tumours:
A malignant skin cancer
A malignant skin cancer

  • These are cancers
  • Cells in these tumours have gone wrong and start to multiply
  • Can damage other tissue or organs in your body
  • Cells from these tumours can seep into your blood and so spread the cancer
  • These tumours should be removed.