Knowledge of the impact of gene expression profiling could allow optimisation of chemotherapy regimens for individual patients. It could ensure that patients do not receive a particular form of chemotherapy if it is unlikely to benefit them, and in these circumstances an alternative form of chemotherapy that may prove beneficial could be selected. This information will therefore allow chemotherapy to be tailored to the individual tumour. It may help identify those patients with a poorer prognosis who could be selected for further therapy post surgery or a different treatment strategy at the outset.