Next-Generation Sequencing of Endobronchial Ultrasound Transbronchial Needle Aspiration Specimens in Lung Cancer

Endobronchial Ultrasound Guided Transbronchial Needle Aspiration and Next Generation Sequencing Yields

PURPOSE

The use of endobronchial ultrasound (EBUS) is standard practice for lung cancer diagnosis and staging. Next generation sequencing (NGS) for detection of genetic alterations is recommended in advanced, non-squamous, non-small-cell lung cancer (NSCLC). Existing protocols for NGS testing are minimal and reported yields vary. This study aimed to determine the yield of EBUS samples obtained for NGS using a sampling protocol at our institution and assess predictive factors to form collection protocols.

METHODS

We reviewed EBUS bronchoscopies from 2016 to 2021 with non-squamous NSCLC diagnoses. For target lesions suspected to be malignant, the sampling protocol was: (a) two slides for on-site evaluation, (b) three to five fine needle aspirations rinsed into saline for immunohistochemical staining and in-house molecular markers, and (c) additional three to five rinses for NGS. Sufficiency for NGS processing was determined by the pathology department.

RESULTS

Two hundred and seventy-eight non-squamous NSCLC samples were obtained by EBUS (205 adenocarcinoma; 73 not otherwise specified). EBUS was performed under general anesthesia in 75.5% of cases. The overall sample adequacy for NGS testing was 57.5%. Higher adequacy rates were observed when protocol was adhered to 66.0% versus 37.2% (p < 0.001). There was no statistically significant difference based on the size of the lesion or location of the sample.

CONCLUSION

When a protocol of three to five dedicated needle rinses for NGS was followed, we nearly doubled our sample adequacy rate for NSG as compared to standard care. Studies are needed to determine the ideal collection and processing modality to preserve tissue samples for genetic sequencing.

Comparison of the harvest volume between maneuvers of endobronchial ultrasound-guided transbronchial needle aspiration including the "cross-fanning technique"

Recently, a certain volume of biopsy specimens has been required for genetic testing of tumors using endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). This study aimed to verify the superiority of our newly devised EBUS-TBNA biopsy technique, the "cross-fanning technique," which combines rotation and up-down maneuvers, by comparing its harvest volume with that of other maneuvers. Using a bronchoscope simulator, ultrasonic bronchoscope, and 21-gauge puncture needle, we compared the weight of silicone biopsy specimens obtained by the following 4 procedures: Conventional maneuver; Up-down maneuver; Rotation maneuver, and; Cross-fanning technique. Each procedure was repeated 24 times in total, rotating the sequences of the maneuvers, and the operator/assistant pair to align the conditions. The means ± standard deviations of the sample volumes for each puncture technique were as follows: 2.8 ± 1.2 mg; 3.1 ± 1.6 mg; 3.7 ± 1.2 mg, and; 3.9 ± 1.2 mg. There was a significant difference between the 4 groups (P = .024). The post hoc test showed a statistically significant difference between techniques A and D (P = .019). This study showed that the cross-fanning technique might contribute to the increased volume of tissue samples obtained by EBUS-TBNA biopsy.

Prospective Optimization of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration Lymph Node Assessment for Lung Cancer: Three Needle Agitations Are Noninferior to 10 Agitations for Adequate Tumor Cell and DNA Yield

Introduction

Methods

Results

Conclusions

Advanced non-small cell lung cancer: Rapid evaluation of EGFR status on fine-needle cytology samples using Idylla

Advanced non-small cell lung cancer (NSCLC) needs to be managed rapidly; therefore, a rapid assessment of the epidermal growth factor receptor (EGFR) status is mandatory. Computed Tomography (CT)-guided or Ultrasound (US)-guided Fine-Needle Aspiration Cytology (FNAC) allows a rapid diagnosis of both primary and metastatic tumor through rapid on-site evaluation (ROSE) and the proper management of diagnostic material. Idylla (Biocartis, Mechelen, Belgium) is an automated RT-PCR system which evaluates the mutational status of specific genes in less than two hours. In this study, the EGFR mutational status in advanced NSCLC was analyzed on 28 FNAC samples with Idylla. After ROSE, residual FNAC material and/or additional passes were pipetted into the Idylla EGFR cartridge. Patients endorsed a consent form before carrying out the analysis. Results were controlled by pyrosequencing. Adequate EGFR status was obtained in 26/28 cases (22 wild type and 4 mutated). Mutated cases harbored EGFR Exon 19 deletion and L858R point mutation. In 2/28 cases the analysis failed. The combination of FNAC, ROSE and Idylla is a rapid, accurate and effective method that can be conveniently used to assess EGFR status in advanced NSCLC.

Is tissue still the issue in detecting molecular alterations in lung cancer?

Molecular biomarker testing of advanced-stage NSCLC is now considered standard of care and part of the diagnostic algorithm to identify subsets of patients for molecular-targeted treatment. Tumour tissue biopsy is essential for an accurate initial diagnosis, determination of the histological subtype and for molecular testing. With the increasing use of small biopsies and cytological specimens for diagnosis and the need to identify an increasing number of predictive biomarkers, proper management of the limited amount of sampling materials available is important. Many patients with advanced NSCLC do not have enough tissue for molecular testing and/or do not have a biopsy-amenable lesion and/or do not want to go through a repeat biopsy given the potential risks. Molecular testing can be difficult or impossible if the sparse material from very small biopsy specimens has already been exhausted for routine diagnostic purposes. A limited diagnostic workup is recommended to preserve sufficient tissue for biomarker testing. In addition, tumour biopsies are limited by tumour heterogeneity, particularly in the setting of disease resistance, and thus may yield false-negative results. Hence, there have been considerable efforts to determine if liquid biopsy in which molecular alterations can be non-invasively identified in plasma cell-free ctDNA, a potential surrogate for the entire tumour genome, can overcome the issues with tissue biopsies and replace the need for the latter.

Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration for Diagnosis and Staging of Lung Cancer

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS TBNA) is fundamental to the diagnosis of lung cancer, as many patients present with more advanced stages of lung cancer, with enlarged hilar and mediastinal lymph nodes. It also represents a way to sample pulmonary masses directly to make the diagnosis, whereby no other accessible tissue is present and the mass sits adjacent to a large central airway. Very importantly also, EBUS TBNA is the widely accepted first procedure in lung cancer staging. A combined procedure of EUS TBNA can be performed to improve diagnostic accuracy.

Diff-Quik Cytology Smears from Endobronchial Ultrasound Transbronchial Needle Aspiration Lymph Node Specimens as a Source of DNA for Next-Generation Sequencing Instead of Cell Blocks

BACKGROUND

Next-generation sequencing (NGS) in lung cancer specimens from endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) is usually performed on formalin-fixed paraffin-embedded cell block material.

OBJECTIVES

Since DNA can be damaged by this process, we investigated the potential of using DNA extracted from Diff-Quik cytology smears made for rapid on-site evaluation during EBUS-TBNA.

METHODS

In a prospective study, 67 patients undergoing diagnostic EBUS-TBNA were ana-lysed. We compared cell blocks and smears for DNA yields and sequencing (TruSeq Amplicon Cancer Panel) outcomes. Smears were also evaluated for tumour cell fraction and overall cellularity (cell count).

RESULTS

Primary lung cancer was diagnosed in 64 patients and metastatic malignancy in 3 patients. The DNA yield from smears was significantly higher than that obtained from matched cell blocks (mean 1,740 vs. 434 ng; p = 0.001). For 33 cases with matched smears and cell blocks the mutation profiles were similar. Smears with abundant malignant cells (using a cut-off of > 25% tumour cell fraction and > 1,000 cells) accurately predicted high (> 50 ng) DNA yield and therefore success in triaging samples to sequencing. In terms of tissue workflow, using only smears as source DNA for sequencing was an improvement in the use of only cell blocks (54/67 [80.6%] vs. 41/67 [61.2%]); however, the use of cell blocks when smears were not available or did not yield sufficient DNA further improved the success rate to 62/67 (92.5%) cases.

CONCLUSION

We recommend smears in laboratory workflows as the primary source of DNA for NGS following an EBUS procedure.

Molecular testing on endobronchial ultrasound (EBUS) fine needle aspirates (FNA): Impact of triage

BACKGROUND

Endobronchial ultrasound (EBUS)-guided fine needle aspiration (FNA) is performed to diagnose and stage lung cancer. Multiple studies have described the value of Rapid On-Site Evaluation (ROSE), but often the emphasis is upon diagnosis than adequacy for molecular testing (MT). The aim was to identify variable(s), especially cytology-related, that can improve MT.

METHODS

A search for EBUS-FNAs with ROSE was conducted for lung adenocarcinomas or when this diagnosis could not be excluded. All such cases underwent reflex MT on cell blocks. The impact of cytology-related variables [i.e., number of pass(es), dedicated pass(es) directly into media, cytotechnologist (CT), laboratory technician (LT) and triage with 1 or >1 cytologist] was evaluated. The latter category was divided into Group A [ROSE, triage and slide preparation by cytopathologist (CP) and CT at start of the procedure] and Group B (ROSE only by CT or by CT/CP after start of procedure; triage and slide preparation by CT or clinical staff). The impact of all these variables on MT was assessed.

RESULTS

A total of 100 cases were identified, and 79 had sufficient tissue for MT. Of all variables evaluated, MT was positively affected by performing a direct dedicated pass (P = 0.013) and ROSE by Group A (P = 0.033).

CONCLUSIONS

ROSE with appropriate triage, including performing a dedicated pass and proper slide preparation, improves MT, and this is enhanced by having >1 cytologist at the start of the procedure. In the era of personalized medicine, "adequate" should denote sufficient tissue for diagnosis and MT.