Cancer cells show unchecked rapid growth beyond tissue boundaries that is no longer stopped by normal control mechanisms. Due to this rapid growth, the metabolism of cancer cells is altered compared to that of cells that grow normally. Cancer cells use this metabolism to provide molecular building blocks and to meet their high energy needs. It has also been known for some time that metabolic intermediates activate specific receptors on the surface of cells. One such metabolite is succinate, which specifically activates a receptor found in various types of tumor.