The cause of many cancers is not yet known. Most cancers are often attributed to our lifestyle habits or by substances in the environment that affect our bodies.

The major causes of cancer are thought to include smoking, sun exposure, diet, chemicals and asbestos. Cancer causing substances are called carcinogens.

Cancer is not an infectious disease. It cannot be passed on to friends or relatives, or anyone else like a cold or the flu.

People who have a family history of some cancers, such as breast and colorectal cancer, may have a higher risk of developing that cancer. In a very small number of families, a change in the gene that controls cell growth is passed on from one generation to the next. Not all family members experience this change. Although those individuals who do, may have a higher than usual chance of developing cancer.