While current mutational analyses comprise exons 19 and 21 in which the majority of EGFR-mutations occur, this study aims at investigating the relevance of exon 18 and 20 mutations. Therefore, the investigators analyse 500 routine tumor samples with respect to the above mentioned exons and correlate the results to the clinical outcome. This approach will enable us to potentially identify patients that might in the future benefit from targeted therapy (EGFR-inhibition).