The Role of Molecular Pathology in Non-Small-Cell Lung Carcinoma—Now and in the Future

In recent years, better understanding of the molecular biology of non-small-cell lung carcinoma (NSCLC) has led to a revolution in the work-up of these neoplasms. As a pathology diagnosis, “NSCLC” without further attempt at subclassification is no longer accepted as a standard of care; separating squamous cell carcinoma from adenocarcinoma and large-cell carcinoma carries implications for prognosis and treatment decisions. Currently, detection of the presence in NSCLC of mutations involving the epidermal growth factor receptor (EGFR) gene and fusion of the N-terminal portion of the protein encoded by EML4 (echinoderm microtubule-associated protein-like 4 gene) with the intracellular signaling portion of the receptor tyrosine kinase encoded by ALK (anaplastic lymphoma kinase gene)—that is, EML4–ALK—and variants has become routine in many centres because patients having tumours harbouring such alterations might benefit from tyrosine kinase inhibitors as part of their treatment regimen. The purpose of the present review is to highlight important aspects of the screening for molecular derangements in NSCLC and to briefly discuss the emergence of possible future biomarkers.