Cancer is difficult
to treat because of the fact that it can spread around the body. Cancer cells
break away from the original primary tumour and spread through the bloodstream
or the lymphatic system, forming new secondary tumours in organs such as the
lungs, liver or brain. Scientists call this process metastasis.
There is the
’seed and soil’ concept – spreading cancer cells are like seeds from rogue
weeds, spreading around a garden. But they can only root and grow if they land
in suitable soil – namely particular parts of the body that can support and
maintain their growth.