RAS (KRAS and NRAS) mutations confer resistance to anti-EGFR monoclonal antibodies, and act as a negative predictive marker for these therapies. The National Institute for Clinical Excellence (NICE) has approved the use of Cetuximab and Panitumumab for the treatment of metastatic colorectal cancer in patients who carry normal, “wild-type” RAS genes. RAS testing is mandatory prior to their prescription.
Please note tissue handling, tissue fixation, time between cutting and staining and excessive drying can lead to loss of expression. Fixatives containing alcohol should not be used and use of Bouin’s fixative will preclude testing by FISH methods.
A copy of the original Pathology report where possible.