Elevated expression of the multi-marker model was observed in tumors with a squamous cell histology, relative to adenocarcinoma cases (p = 0.019), driven in part by higher levels of CYFRA 21-1 (p < 0.0001) and OPN (p = 0.013) in squamous cell carcinomas (unpublished data). This evidence concerns the gene SPP1 and adenocarcinoma.