Preanalytic parameters in epidermal growth factor receptor mutation testing for non–small cell lung carcinoma: A review of cytologic series

Abstract

The results from molecular assays can be affected significantly by the preanalytic condition of cytologic samples. The authors review current knowledge on the use of cytologic samples for epidermal growth factor receptor (EGFR) mutation testing in non–small cell lung cancer with a focus on preanalytic parameters. A systematic electronic search of the MEDLINE database was performed to identify original articles that reported the use of cytologic samples for EGFR molecular analysis and included a minimum of 100 samples. The information collected included author(s), journal, and year of publication; number of patients and samples; sampling method; type of preparation; type of fixative; staining techniques; mutation analysis techniques; tumor cellularity; the percentage of tumor cells; data on DNA quantity, quality, and concentration; failed assays; and the mutation rate. EGFR mutation analysis was conducted on 4999 cytologic samples from 22 studies that fulfilled the inclusion criteria. Fine‐needle aspirates and pleural effusions were the most common types of specimens used. DNA was mainly extracted from cell blocks and smears, and the most commonly reported fixatives included formalin, ethanol, and CytoLyt. Cellularity assessments and DNA yields were available from 5 studies each. The average success rate for the assays that used cytologic specimens was 95.87% (range, 85.2%‐100%). The mutation rate ranged from 6% to 50.46%, and a higher mutation detection rate and lower numbers of insufficient cases were reported for pleural effusions and lymph node samples from endobronchial ultrasound‐guided transbronchial needle aspiration compared with histologic specimens. Low cellularity and a low percentage of tumor cells were associated with higher test failure rates. Future guidelines should consider the current data for specific recommendations regarding cytologic samples. Cancer (Cancer Cytopathol) 2015;123:633–643. © 2015 American Cancer Society.

The value of cell block based on fine needle aspiration for lung cancer diagnosis

“…Thus, we recommended using CB and ICC to evaluate cytological samples derived from FNA. CB also allows for genetic testing and prognostic assessment via PCR, FISH and IHC (22)(23)(24)(25). CB is helpful for diagnosing and subtyping advanced lung cancer, determining precise treatments, and preserving cytological specimens.…”

Molecular Testing of Non–Small Cell Lung Carcinoma Diagnosed by Endobronchial Ultrasound–Guided Transbronchial Fine-Needle Aspiration: The Cleveland Clinic Experience

“…Given the diversity of cytopathologic specimen types and the different methods of fixation and processing available, options for procuring DNA from cytologic specimens for molecular analysis vary; material can be successfully obtained from cell blocks, smears, cytospins, and liquid-based preparations. 7,9,11,12,14,[19][20][21][22][23][24][25] Most commonly, cell blocks are used for molecular testing on cytopathologic specimens. 21 The cell block closely approximates surgical pathology material; tissue fragments from cytopathologic specimens are embedded in paraffin and are sectioned akin to surgical specimens.…”

“…29 Although liquid-based cytology specimens are not commonly used for molecular testing of lung adenocarcinomas, 21 a few groups have reported their utility. 7,12,14,25 In our laboratory, we have found that the liquid-based cytology specimen is an excellent resource for EGFR mutation analysis and ALK FISH.…”

Improving Molecular Testing and Personalized Medicine in Non-Small-Cell Lung Cancer in Ontario

“…Tumour cellularity in bronchial wash specimens 24 -and also in bronchial biopsy samples 25,26 -is often relatively low. The worst results with respect to EGFR mutation detection rates have been reported for bronchial washings or brushings and sputum 27 . Bronchial biopsy specimens can also show crush artifact, impairing downstream immunohistochemistry (ihc) or fluorescence in situ hybridization.…”

“…Whether cytology or biopsy specimens are obtained, tumour cellularity is the key determinant of the likelihood of successful molecular testing [45][46][47][48] ; both techniques can potentially yield adequate material for diagnostic molecular tests 49 . With respect to cytology specimens, preparation of a cell block is still preferred 24,50 , but other specimens are also suitable for analysis 27 . It is important to recall that molecular testing should still be attempted in specimens in which it is unclear whether the sample will meet all technical requirements.…”