PRIMARY OBJECTIVES:
I. To validate a novel 4-protein signature's ability to subtype non-small cell lung cancer (NSCLC) in a treatment-naive, multi-institutional cohort, Cancer and Leukemia Group B (CALGB) 9761.
SECONDARY OBJECTIVES:
I. To estimate the NSCLC misclassification rate in a multi-institutional clinical-trial setting for stage 1 NSCLC (adenocarcinoma versus squamous cell).
OUTLINE:
Previously collected tissue samples are analyzed via hematoxylin and eosin (H\&E) staining and immunohistochemistry (IHC).
