Molecular Profiling of Cytology Cell Block Samples in Non-Small Cell Carcinoma of Lung: A Large Metropolitan Institutional Experience

Document Type

Conference Proceeding

Publication Date

3-19-2022

Publication Title

Mod Pathol

Abstract

Background: Identifying targetable mutations is the standard of practice in the management of advanced non-small cell lung carcinoma (NSCLC). Candidates for assessment of targetable mutations often have diagnostic material limited to cytologic specimens. We aimed to 1) Evaluate the feasibility & success of detecting genetic alterations using molecular & Florescent In-Situ Hybridization (FISH) testing based only on cell block material from patients with NSCLC 2) Compare our adenocarcinoma mutations distribution results with published data from The Cancer Genome Atlas (TCGA) of treatment naive lung adenocarcinoma. Design: We identified 102 NSCLC cases from 2019-2020 that were tested for targeted Next Generation Sequencing (NGS) panels and ALK & ROS1 FISH using only cell block material. Clinicopathologic findings including age, gender, specimen source, type of NSCLC, clinical stage, type of assay, & sequencing results were recorded. Results: There were 54% males with median age of 70 (range 48-88). Tumor types included: 74/102 adenocarcinoma, 12/102 squamous cell carcinoma, 16/102 poorly differentiated & other carcinomas. Sources of tissues were: Lung (19/102), mediastinal lymph node (58/102), pleural fluid (20/102), & distant metastasis (5/102). Clinical stages were as follows: II=6 cases, III=15 cases, IV=81 cases. NGS was performed on 101 cases; 6 of which showed insufficient tumor quantity (QNS). 54/95 revealed pathogenic variants while no alterations detected in 34 cases & 7 cases showed variant of undetermined significance (VOUS). The average number of alterations per case was 1.1 (range 0-6) & average VOUS per case was 0.3 (range 0-5). Figure 1 depicts the spectrum of pathogenic genes detected in 54 cases. RNA Fusion panel was performed in 42 cases; 3 QNS cases & only 1 case showed SLC34A2-ROS1 fusion. 2/35 cases were positive by ALK FISH & 1 case was QNS. 1/10 case was positive for ROS1 FISH. Conclusions: 57% patients showed genomic variants detected by NGS using cell blocks only. The proportion & type of gene alterations detected is concordant with those normally detected in surgical pathology specimens of lung adenocarcinoma (except for TP53 & STK11 likely due to sequencing coverage limited to hotspot exons in our cohort). Molecular testing in cytology specimens is feasible & is consonant with larger sample types. (Figure Presented) (Figure Presented).

PubMed ID

Not assigned.

Volume

35

Issue

SUPPL 2

First Page

239

Last Page

240

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