Biomarkers in Blood Samples From Patients With Refractory Non-Small Cell Lung Cancer Previously Treated With Sorafenib Tosylate

OBJECTIVES: * To determine the mutation rates of BRAF, KRAS, and EGFR in patients with non-small cell lung cancer treated with sorafenib tosylate on protocol ECOG-2501. * To determine the association between BRAF, KRAS, or EGFR mutation status and clinical benefits in patients treated with this regimen. OUTLINE: This is a multicenter study. DNA is isolated from archived plasma samples and analyzed for BRAF, KRAS, and EGFR mutations.