Detection of Epidermal Growth Factor Receptor Mutations in a Few Cancer Cells from Transbronchial Cytologic Specimens by Reverse Transcriptase-Polymerase Chain Reaction

Anaplastic lymphoma kinase gene analysis as a useful tool for identifying primary unknown metastatic lung adenocarcinoma

A 55-year-old woman was admitted for an evaluation of a mediastinal mass, bilateral cervical lymphadenopathy and a left breast tumor. Although pathology revealed a diagnosis of breast cancer, the cervical lymph nodes differed from the breast lesion. An anaplastic lymphoma kinase (ALK) gene analysis revealed ALK rearrangement in the cervical lymph nodes only, which were therefore diagnosed as reflective of metastasis of lung adenocarcinoma. The mediastinal tumor was also diagnosed as an ALK-positive lung adenocarcinoma based on its therapeutic response. ALK gene analyses can be used to identify primary lesions in patients with cancers of unknown primary sites.

Effective assessment of egfr mutation status in bronchoalveolar lavage and pleural fluids by next-generation sequencing

PURPOSE

The therapeutic choice for patients with lung adenocarcinoma depends on the presence of EGF receptor (EGFR) mutations. In many cases, only cytologic samples are available for molecular diagnosis. Bronchoalveolar lavage (BAL) and pleural fluid, which represent a considerable proportion of cytologic specimens, cannot always be used for molecular testing because of low rate of tumor cells.

EXPERIMENTAL DESIGN

We tested the feasibility of EGFR mutation analysis on BAL and pleural fluid samples by next-generation sequencing (NGS), an innovative and extremely sensitive platform. The study was devised to extend the EGFR test to those patients who could not get it due to the paucity of biologic material. A series of 830 lung cytology specimens was used to select 48 samples (BAL and pleural fluid) from patients with EGFR mutations in resected tumors. These samples included 36 cases with 0.3% to 9% of neoplastic cells (series A) and 12 cases without evidence of tumor (series B). All samples were analyzed by Sanger sequencing and NGS on 454 Roche platform. A mean of 21,130 ± 2,370 sequences per sample were obtained by NGS.

RESULTS

In series A, EGFR mutations were detected in 16% of cases by Sanger sequencing and in 81% of cases by NGS. Seventy-seven percent of cases found to be negative by Sanger sequencing showed mutations by NGS. In series B, all samples were negative for EGFR mutation by Sanger sequencing whereas 42% of them were positive by NGS.

CONCLUSIONS

The very sensitive EGFR-NGS assay may open up to the possibility of specific treatments for patients otherwise doomed to re-biopsies or nontargeted therapies.

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.