Chromogenic in situ hybridization to detect EGFR gene copy number in cell blocks from fine-needle aspirates of non small cell lung carcinomas and lung metastases from colo-rectal cancer

Giovanni Simone,Vincenza Rubini,Marcella Mottolese,Anita Mangia,Flavia Novelli,Andrea Malfettone,Irene Terrenato,Anna Di Benedetto,Michele Siciliano

doi:10.1186/1756-9966-29-125

Abstract

BackgroundSeveral studies demonstrated that epidermal growth factor receptor (EGFR) gene copy number (GCN) correlates to the response to tyrosine kinase inhibitors in non small cell lung cancer (NSCLC) and to anti-EGFR monoclonal antibodies (MoAbs) in metastatic colorectal cancer (CRC). In the presence of lung nodules, cytology is often the only possible diagnostic approach. Chromogenic in situ hybridization (CISH) is an alternative technique to fluorescence in situ hybridization (FISH), but its feasibility in detecting EGFR GCN in cell blocks from fine-needle aspiration cytology (FNAC) of lung nodules has not yet been established.MethodsWe evaluated the feasibility of CISH on 33 FNAC from 20 primary NSCLC (5 squamous carcinomas, 8 large cell carcinomas and 7 adenocarcinomas) and 13 lung metastases from CRC.ResultsOf the 33 FNAC analyzed by CISH, 27 (82%) presented a balanced increase in EGFR gene and chromosome 7 number: 10 cases (30%) showed a low polysomy, 15 (45%) a high polysomy and 2 (6%) NSCLC were amplified. No significant differences between NSCLC and CRC lung metastases were found in relation to disomic or polysomic status. In addition, no correlation between EGFR GCN and EGFR immunohistochemical overexpression was found. Furthermore, we compared CISH results with those obtained by FISH on the same samples and we found 97% overall agreement between the two assays (k = 0.78, p < 0.0001). Two cases were amplified with both assays, whereas 1 case of NSCLC was amplified by FISH only. CISH sensitivity was 67%, the specificity and positive predictive value (PPV) was 100%, and the negative predictive value (NPV) was 97%.ConclusionsOur study shows that CISH is a valid method to detect EGFR GCN in cell blocks from FNAC of primary NSCLC or metastatic CRC to the lung.

Highlights

Epidermal growth factor receptor (EGFR) is a member of the erbB family of tyrosine kinases (TK) receptor proteins, that play an important role in tumor progression [1]
According to poor clinical information obtained from the immunohistochemistry (IHC), the interest in epidermal growth factor receptor (EGFR) gene status increased after Moroni et al [10] proposed that in colorectal cancer (CRC) the response to anti EGFR treatment with cetuximab is related to EGFR gene copy number (GCN) and Lynch et al [11] showed that, in advanced non small cell lung cancer (NSCLC), in-frame deletion or missense mutations in the EGFR TK domain can predict the response to therapy with gefinitib
In a retrospective series of 33 pulmonary tumors, we investigated the feasibility and reliability of Chromogenic in situ hybridization (CISH) performed in cell blocks obtained from fine-needle aspiration cytology (FNAC), to detect EGFR gene copy number both in primary NSCLC and metastatic CRC (mCRC) lung nodules

Summary

Introduction

Epidermal growth factor receptor (EGFR) is a member of the erbB family of tyrosine kinases (TK) receptor proteins, that play an important role in tumor progression [1]. The binding EGFR/ligand leads to activation of the TK, inducing cell growth, inhibition of. The anti-EGFR erlotinib and gefitinib have undergone extensive clinical testing demonstrating clinical activity in NSCLC [6]. In this context, there is a need for methods enabling response prediction in order to select those patients most likely to benefit from treatment. Several studies demonstrated that epidermal growth factor receptor (EGFR) gene copy number (GCN) correlates to the response to tyrosine kinase inhibitors in non small cell lung cancer (NSCLC) and to antiEGFR monoclonal antibodies (MoAbs) in metastatic colorectal cancer (CRC). Chromogenic in situ hybridization (CISH) is an alternative technique to fluorescence in situ hybridization (FISH), but its feasibility in detecting EGFR GCN in cell blocks from fine-needle aspiration cytology (FNAC) of lung nodules has not yet been established

Methods

Results

Conclusion