The question is not everybody actually develops cancer in their lifetime. And because on a daily basis we produce anywhere from several to 1000 of these different cancer cells how exactly does our immune surveillance system, our immune system in general actually detect these cancer cells and destroy these cancer cells? Well, since these cancer cells have a slightly different sequence of nucleotides on their DNA they will produce slightly different proteins. And these different proteins that end up on the membrane of these cancer cells can be read by certain white blood cells as being foreign antigens. And when these white blood cells locate these foreign antigens found on the cancer cells they can basically mark or label these cancer cells for destructions. So let's actually discuss what the different types of cells are in our immune system that basically are used to control and destroy these cancer cells.