Given the histologic and molecular intra- and inter-tumor heterogeneity of lung tumors, and the biologic diversity of each histologic entity, we first sought to define p16Ink4A-expression heterogeneity, and subsequently to characterize the prognostic significance of p16Ink4A testing in lung cancers using a semi-quantitative score. This evidence concerns the gene CDKN2A and Neoplasm of the lung.