Erbitux, originally used for colorectal cancer, was found to be ineffective in 40 percent of the patients due to a mutated KRAS gene. For colorectal, they now do a biomerker marker test before using to see if a person has the mutated gene or wild type (normal) KRAS gene, which seems Erbitux works with, and even insurance can deny use based on mutation. They do not do the biomarker for Head and Neck Cancer, and say, and I was told, it doesn't apply for HNC. Charm had ascertained Erbitux did not work in 5% of HNC. Also interesting is a large percentage of the mutations appear to be in the Southern belt area. I read one suggestion having to do with sun exposure, but haven't read further about that.