Several different monoclonal antibodies have been shown to have benefit in patients with advanced colo-rectal cancer. These work by blocking receptors vital to the tumour. One (Bevacizimab) blocks the effects of vascular endothelial growth factor (VEGF). The beneficial effects of this antibody prove the benefical effects of strategies targeted against angio-genesis. One of the effects of VEGF is to cause expression of the endothelial growth factor receptor (EGFR). Binding of growth factors to this receptor will then cause the tumour to grow. Blockage of teh EGFR by the antibody (Cetuximab), has also been shown to offer beneficial effects in patients with advanced colo-rectal cancer. The role of these drugs in the adjuvant setting is not clear at this point in time.