Cells in the body normally divide in a controlled way to make new cells for growth and repair. Cancer is the result of changes in the genetic material of a cell, called mutations, that lead to uncontrolled growth and division. The cell keeps dividing and forms a lump of cells called a tumour.
Not every tumour is cancer. A benign tumour grows in one place and stays enclosed within a membrane. It does not invade other tissues and is not usually dangerous. A malignant tumour is cancer. Its cells invade neighbouring tissues and can break off and travel in the blood to other parts of the body, where they form secondary tumours.
Cancer is a non-communicable disease. Risk factors include smoking, obesity, UV radiation, some viruses and inherited genes, but no single factor is the only cause. Finding a cancer early, before it has spread, gives the best chance of successful treatment.
