Biomarker testing in non-small cell lung carcinoma: Rationale and practical considerations

The treatment of non-small cell lung carcinoma has undergone a paradigm shift over the last decade. Treatment with targeted agentsis now the standard of care for many patients. Consequently, precise histological typing and triage of tissue for molecular testing are vital components of the pathologic evaluation of small biopsies from these patients. The indications for 2 commonly used chemotherapeutic agents, premetrexed and bevacizumab, are linked to histological subtype in that the use of these agents is contraindicated in cases of squamous cell carcinoma. Treatment with endothelial growth factor receptor or ALK inhibitors is mandated by the current National Comprehensive Cancer Network guidelines for patients with metastatic disease whose tumors harbor these respective mutations. Although molecular testing at most institutions is done using single-gene tests, migration to multiplex assays is likely to occur in the near term to midterm as additional Food and Drug Administration-approved targeted therapies become available. In most venues, formalin-fixed paraffin-embedded tissue is most suitable for biomarker testing and can be reliably generated from many cytology specimens.