The body is made up of millions of tiny building blocks called cells. These cells then group together to form tissues and organs within our bodies. Normal, healthy cells grow and divide in a controlled fashion, creating new cells. This enables the body to grow, repair and heal. The cell stops reproducing and dies naturally when it’s old and no longer needed.
A cancerous tumour is called a malignant tumour. It can grow into nearby tissue and invade surrounding organs. Sometimes, cancer cells spread from where the cancer first started (the primary site) to other parts of the body. They can travel through the blood or lymphatic system.
For more information on what radiotherapy is and how it works, please see:What is radiotherapy?