Background: Lung cancer is the leading cause of cancer-related death and one of the most common cancer types worldwide. Epidermal growth factor receptor (EGFR) has been shown to be an important therapeutic target in non-small cell lung cancer. Kirsten rat sarcoma viral oncogene homologue (KRAS) is a downstream signalling molecule in the EGFR pathway. Lung cancer patients with EGFR mutations respond to tyrosine EGFR inhibitor therapy, in contrast, patients with KRAS mutations do not benefit of such treatment. Methods: This study investigates the frequency of EGFR and KRAS mutations in non-small cell lung cancer patients. Fifty-one lung cancer patients with primary non-small cell lung cancer diagnosed between 1995 and 2005 in the Uppsala-Örebro region were analysed by Sanger sequencing and Pyrosequencing to determine the mutation status of these genes. Results: Five EGFR mutations were found in four patients (8%), two deletions in exon 19, one point mutation in exon 20 and two point mutations in exon 21. KRAS mutations were found in 12 patients (24%), ten codon 12 mutations and two codon 61 mutations. Conclusions: This study confirms previous observations regarding the frequency of EGFR and KRAS mutations in non-small cell lung cancer. Mutations in EGFR and KRAS were mutually exclusive, indicating that both mutations present relevant tumorigenic genomic aberrations.

<p><strong>Background: </strong>Lung cancer is the leading cause of cancer-related death and one of the most common cancer types worldwide. Epidermal growth factor receptor (EGFR) has been shown to be an important therapeutic target in non-small cell lung cancer. Kirsten rat sarcoma viral oncogene homologue (KRAS) is a downstream signalling molecule in the EGFR pathway. Lung cancer patients with <em>EGFR </em>mutations respond to tyrosine EGFR inhibitor therapy, in contrast, patients with <em>KRAS </em>mutations do not benefit of such treatment.</p><p><strong>Methods: </strong>This study investigates the frequency of <em>EGFR </em>and <em>KRAS </em>mutations in non-small cell lung cancer patients. Fifty-one lung cancer patients with primary non-small cell lung cancer diagnosed between 1995 and 2005 in the Uppsala-Örebro region were analysed by Sanger sequencing and Pyrosequencing to determine the mutation status of these genes.</p><p><strong>Results: </strong>Five <em>EGFR </em>mutations were found in four patients (8%), two deletions in exon 19, one point mutation in exon 20 and two point mutations in exon 21. <em>KRAS </em>mutations were found in 12 patients (24%), ten codon 12 mutations and two codon 61 mutations.</p><p><strong>Conclusions: </strong>This study confirms previous observations regarding the frequency of <em>EGFR </em>and <em>KRAS </em>mutations in non-small cell lung cancer. Mutations in <em>EGFR </em>and <em>KRAS </em>were mutually exclusive, indicating that both mutations present relevant tumorigenic genomic aberrations.</p>