Based on our data, we propose that pathologists should perform combined immunohistochemistry staining of lung tumor samples for Rb S249 phosphorylation and for p39 protein expression to aid in the clinical assessment of SCC tumor staging, histological NSCLC subtyping and metastatic potential in those patients who are not amenable to tumor resection and for whom treatment must be informed predominantly by evaluations of small tumor biopsies. This evidence concerns the gene RB1 and non-small cell lung carcinoma.