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The term ‘cancer’ refers to a disparate group of malignant
diseases that have one thing in common: uncontrolled division of the cells of an organ or tissue. A
mass of cancer cells is known as a tumour. The uncontrolled
growth of a tumour results in destruction of surrounding healthy tissue. Spread of tumour cells via
the blood or lymphatic system can lead to the formation of secondary growths, or metastases,
in other organs or tissues.
The rate of growth of a tumour depends on
the speed with which the cells divide. The cells of some tumours divide very rapidly, while those of
others divide slowly. The blood supply of a tumour is crucial in this respect, since blood transports
nutrients and oxygen to the tumour cells and thereby promotes growth of the tumour. Some tumours can
cause new blood vessels to grow into the tumour from adjacent areas. Such tumours have a richer supply
of nutrients and oxygen and therefore grow faster. |
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