Coloured magnetic resonance imaging (MRI) scan showing the thorax and spine (right) of a 60 year old man with bronchial carcinoma (lung cancer) that has spread (metastasised) to the spine, forming secondary tumours (red spots in spine). Metastasis occurs when cells from a tumour break off and are transported to other parts of the body via blood or lymph vessels. This is also known as advanced cancer, or stage 4 cancer. At this stage it can not always be cured but radiotherapy and chemotherapy can be used to control symptoms.