Why are cancer cells dangerous?

In some tumours, the cells stay in the same place and as the tumour stops growing before it gets very large - often because it simply runs out space to grow. These are called benign tumours and they are not normally dangerous. We all have benign tumours, such as moles and warts. read more

They come in many different types: liver cells, brain cells, blood cells and so on. In the normal adult, cells only grow and divide slowly and under very tight control to make sure that the number of cells in each tissue stays the same. Cancer begins when one cells changes and starts growing and dividing rapidly and out of control. read more