EGFR and neoplasm: The cohort was divided into two distinct phenotypes; patients with grade 3 (or higher) toxicity and patients with no or up to grade 2 skin toxicity It was chosen to do so since the occurrence of grade 3 toxicity is of significant clinical relevance; toxicity of this severance might interfere with anti-tumor efficacy due to the need for dose reductions, dose delays and, in some cases, even permanent discontinuation of the EGFR inhibitor.