Cancer begins with an alteration to the structure of DNA that is found in all human cells. This is known as a genetic mutation. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce.

The mutation in the DNA changes these instructions, so that the cells carry on growing. This causes the cells to reproduce in an uncontrollable manner producing a lump of tissue, known as a tumour.  There are over 200 different types of cancer and we don't know the causes of all of these but we do know some.

For further information please click on a link below:

1. NHS Choices
2. Macmillan Cancer Support