Reproducible molecular characterization of non-small cell lung cancer from paraffin

7576 Background: Recommendations exist to aid the clinically relevant non-small cell lung cancer (NSCLC) classification of squamous (SQ) versus adenocarcinoma (AD), including immunohistochemistry (IHC) for TTF1 and p63. We hypothesize that PCR of RNA gene panels may improve the diagnostic accuracy over IHC. Methods: A multi-institutional cohort of NSCLC patients was abstracted for use of IHC in clinical practice. RNA was isolated from routine paraffin sections and a 54-gene Histology by gene Expression Predictor (HEP) was implemented to distinguish SQ, AD, and other NSCLC variants. IHC for TTF1 and p63 was obtained on a subset of patients in a standardized manner. To compare the reproducibility of PCR diagnostics to morphologic diagnosis, a subset of samples was processed as matched pairs from the same tumor, in blinded manner. Results: 493 clinical samples were analyzed from 419 patients. Pathologists obtained any IHC in 22% of the cases, with TTF1 or p63 in