Cancer is a disease that affects the cells of the body.
Every part of your body is made up of cells. Cancer happens when some of the cells that make up your body become abnormal. This can happen by chance. It can also happen as a result of risk factors, or things that increase your chance of getting cancer.
Cancer cells multiply without stopping and become tumours. Tumours are groups of cancer cells that form a swelling or lump. Tumours can affect how the body functions and harm your health. For example, a tumour can grow so large that it damages or obstructs nearby tissues and organs. A tumour can also release chemicals that disrupt the way a healthy body works.
Cancer can start almost anywhere in the body. The place in a person’s body where cancer starts is called the primary site. The type of cancer a person has is usually named after the primary site of their cancer. For example, some people have breast cancer while others have lung cancer.
Cancer can grow at the primary site without spreading to other parts of the body. Sometimes cancer cells break away from the primary site and travel to other places in the body, where new tumours form. This is called metastasis.
It is important to find tumours as early as possible. This is when they are most treatable.