Comprehensive epidermal growth factor receptor gene analysis from cytological specimens of non-small-cell lung cancers

Abstract

Epidermal growth factor receptor (EGFR) gene mutations and increased copy numbers are considered as predictors of response to EGFR tyrosine kinase inhibitors (EGFR-TKI) in non-small-cell lung cancer (NSCLC). Lung cancer diagnosis is often based on cytology alone. However, almost all published data on EGFR gene analyses were obtained from biopsies. This study tested the feasibility of EGFR gene analyses on cytological specimens. Eighty-four cytological specimens from NSCLCs were prospectively analysed for EGFR gene mutation in exons 18 -21 and EGFR gene copy numbers were evaluated by fluorescence in situ hybridisation (FISH). A FISHpositive result was defined according to the criteria by Cappuzzo et al established for biopsies of NSCLCs. Fluorescence in situ hybridisation results of cytological specimens were compared to the FISH results on matching biopsies (n ¼ 33). Initial diagnosis of NSCLC was solely based on cytology in 37 out of 84 (44.0%) patients. Out of 80 NSCLCs, 6 (7.5%) showed EGFR gene mutations. Out of 67 cancers, 45 (67.2%) were FISH positive on cytological specimens. Comparison of FISH showed a FISH-positive result in 21 out of 33 (63.6%) cytological specimens but in only 8 out of 33 (24.2%) matched biopsies. Epidermal growth factor receptor gene analyses are well applicable to cytological specimens. The high FISH-positive rate of NSCLC on cytological specimens contrasts with the low rate on biopsies when previously suggested criteria are used. New criteria for a positive EGFR FISH status to predict response to therapy with EGFR-TKI need to be defined for cytological specimens.

Assessment of Epidermal Growth Factor Receptor and K-Ras Mutation Status in Cytological Stained Smears of Non-Small Cell Lung Cancer Patients: Correlation with Clinical Outcomes

“…They explained this fact by differences in the method of sample fixation between the two types of specimens, favoring methanol over formalin for mutational studies, thus highlighting the importance of preserving high-quality DNA. Savic et al [32] studied the presence of EGFR mutations in NSCLC samples, including some Papanicolau-stained slides from NSCLC patients, using sequencing methods. None of the previous studies provided clinical information on the outcome of the patients treated with TKIs to confirm their predictive value.…”

Target therapy in NSCLC patients: Relevant clinical agents and tumour molecular characterisation

“…Authors of the present study as well as other investigators (68)(69)(70) have demonstrated that EGFR mutation analysis may be performed on a small number of tumour cells (20-30 cells) isolated from a cytological slide, enabling the remaining material to be archived or used for other molecular analyses such as the EML4-ALK FISH test.…”

“…Efforts have therefore been focused on detection of EGFR mutations in cytological samples and the results of several studies have demonstrated that cytological material is suitable and reliable for EGFR mutation analysis (65)(66)(67)(68)(69)(70), such as that for the EML4-ALK FISH test (68). Specifically, paraffin-embedded histological or cytological sections could, compared to cytological smears, result in truncated cells and nuclei, producing more DNA fragmentation and a consequent possible false number of gene copies.…”

The Usage of Cytological Material for Diagnostics of Lung Cancer

“…Безусловно, наилучшим биологиче-ским материалом для получения ДНК является операци-онный материал. Тем не менее различный цитологический материал, включая плевральные жидкости, может исполь-зоваться для молекулярных исследований [19,20]. Клеточ-ный материал, полученный при пункции опухоли легкого и ее метастазов (в том числе плеврального выпота) и брон-хоскопическом исследовании, может иметь гораздо больше опухолевых клеток, чем небольшая биопсия.…”