Cancer is when abnormal cells divide in an uncontrolled way. Some cancers may eventually spread into other tissues. Cancer starts when gene changes make one cell or a few cells begin to grow and multiply too much. This may because a growth called a tumour. A primary tumour is the name for where a cancer starts. Cancer can sometimes spread to other parts of the body – this is called a secondary tumour or a metastasis. Cancer and its treatments can affect body systems, such as the blood circulation, lymphatic and immune systems, and the hormone system. Most cancers start due to gene changes that happen over a person’s lifetime. More rarely cancers start due to inherited faulty genes passed down in families. Many cancers are cured. But in some people cancer can return.Some cancers can’t be cured but treatment is often able to control them for some years. Cancers are divided into groups according to the type of cell they start from. They include Carcinomas, Lymphomas, Leukaemias, Brain tumours, Sarcomas staging and grading give an idea of how quickly a cancer may grow and which treatments may work best. The stage of a cancer means how big it is and whether it has spread.