B. Weynand MD, PhD

Molecular diagnostics on tissue samples obtained through EBUS-TBNA: review on practice guidelines

Summary

Endobronchial ultrasonography is a minimally invasive endoscopic technique that enables a real time transbronchial needle aspiration. Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) specimens have a high diagnostic accuracy in the detection of intrathoracic lymph node metastasis for a variety of malignancies. Predictive biomarker testing is gaining wide importance to tailor the treatment with the largest benefit to the patient. Endobronchial ultrasound guided transbronchial needle aspiration also results in an accurate analysis of molecular alterations (by ImmunoHistoChemistry, Fluorescence In Situ Hybridisation, or gene sequencing) provided that the endoscopist takes sufficient tumour samples and a dedicated cytopathologist is involved in the mastery of the specimens.

Endobronchial ultrasound guided transbronchial needle aspiration samples can be handled in different ways. Liquid-based cytology and smears are mostly used. The choice of the testing method should be based primarily on the nature of the sample to be tested, testing laboratory’s expertise, and available equipment. ImmunoHistoChemistry, Fluorescence In Situ Hybridisation and targeted polymerase chain reaction-based sequencing can be performed on >80% of the endobronchial ultrasound guided transbronchial needle aspiration specimens, as the latter is more sensitive in terms of limit of detection than Sanger sequencing. The next step are the next generation sequencing assays, with only 10–20 ng of DNA sample input per gene mutation, which will minimise rejected samples due to insufficient sample quantity.

(BELG J MED ONCOL 2016;10(1):15–20)

Clinical application of targeted next generation sequencing for lung cancer patients

Summary

The successes of targeted agents in patients with molecularly defined tumours and improvements in genomic technology have generated enthusiasm for incorporating genomic profiling into clinical cancer practice and molecular testing has now become a standard of care for lung cancer. International guidelines recommend testing for EGFR mutations and ALK gene rearrangement to guide patient selection for therapy. However, different potentially targetable oncogenes, such as KRAS, PIK3CA, BRAF, ERBB2 or MET, for which agents are being evaluated, have been proposed as valuable for managing patients with lung cancer. Recently, the development of next generation sequencing has enabled simultaneous detection of many clinically relevant mutations in different genes in a single test. In this study, we have evaluated the clinical utility of targeted next generation sequencing, using a 22 genes panel, for patients with lung cancer on 234 samples, including cytology, biopsies and surgical resections, from two different institutions tested in routine daily practice since validation and accreditation of the method (BELAC ISO15189). On the 234 samples tested, only one case could not be sequenced due to an insufficient quantity of available tissue. Among the 233 cases tested, 223 (95.7%) samples were sequenced successfully. The median turnaround time between reception of the sample in the laboratory and report release was one week. The most frequent mutations were found in TP53 (42.1%) and KRAS (35.9%). Of successfully sequenced cases, 137 potentially actionable mutations were identified in 130 patients (58.3%), including 80 KRAS mutations, 26 EGFR mutations, fourteen BRAF mutations, eight PIK3CA mutations, three PTEN mutations, two ERBB2 insertions, two NRAS mutations and two MAP2K1 mutations. Overall, next generation sequencing can be applied in daily practice even for small samples, such as lung biopsies or cell blocks. Moreover, it provides clinically relevant information for lung cancer patients.

(BELG J MED ONCOL 2015;9(7):272–78)