RESEARCH ARTICLE
HER2 Gene Amplification by Fluorescence In Situ Hybridization (FISH) Compared With Immunohistochemistry (IHC) in 122 Equivocal Gastric Cancer Cases Xiaoyan Liu, MSc, Xiaoling Wang, PhD, Bo Wang, MSc, Guoping Ren, MSc, and Wei Ding, BSc
Objective: To determine the frequency of HER2/neu amplification and the relationship between HER2/neu expression and clinicopathologic features in gastric cancers scored immunohistochemistry (IHC) 2+. Methods: A total of 122 gastric cancer cases scored IHC 2+ were retrospectively analyzed for HER2 amplification by fluorescence in situ hybridization (FISH). The correlation between HER2/neu expression and clinicopathologic features was analyzed. Results: HER2/neu gene was amplified in 17 out of the 122 gastric cancer samples. The concordance rate between IHC and FISH was 13.9%. HER2/neu status was correlated with the age of patients (P < 0.05). Polysomy of CEP17 was demonstrated in 46 cases, 11 of which (23.91%) were amplified for HER2/neu. Within the subgroups, a correlation between CEP17 polysomy and the depth of invasion was observed (P < 0.05). Conclusions: The results highlight the necessity of FISH test for further categorization when gastric cancer cases are scored 2+ by IHC. The value of HER2/neu for a potential role as a negative prognostic factor in the equivocal gastric cancer cases is limited. Key Words: gastric cancer, fluorescence in situ hybridization, HER2/neu (Appl Immunohistochem Mol Morphol 2015;00:000–000)
H
ER2/neu gene (also known as C-erbB-2 gene) is a member of the type-I growth factor receptor family.1 It is located on the long arm of chromosome 17, encoding a 185 kD transmembrane glycoprotein.1 Intracellular signaling and activation of genes controlling cell growth Received for publication November 23, 2014; accepted April 10, 2015. From the Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China. X.L. and X.W. contributed equally. The authors declare no conflict of interest. Reprints: Bo Wang, MSc, Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79# Qingchun Road, Hangzhou, Zhejiang 310003, China (e-mail: wangbo19800623@ sohu.com). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
Appl Immunohistochem Mol Morphol
can be triggered by the HER2/neu oncoprotein. The activation of HER2/neu is also linked with shortened survival, enhanced aggressiveness, and other poor prognostic factors.2 HER2/neu plays an important role in the development of certain solid human tumors. HER2 amplification and overexpression have been proved to be correlated with the pathogenesis of several human cancers, of which breast cancer is the most well defined.3–5 Clinical trials demonstrated that the subset of patients with HER2/neu overexpression could benefit from trastuzumab, a recombinant humanized anti-HER2/neu monoclonal antibody, in advanced and metastatic breast cancer.6 Moreover, the clinical benefit of trastuzumab in patients with inoperable or metastatic advanced gastric or gastroesophageal junction cancer characterized by HER2/ neu positive was also shown in the Trastuzumab for Gastric Cancer (ToGA) study.7 Thus the accurate evaluation on HER2/neu gene status is the first step. A wide variety of techniques has been introduced into the test of the HER2/neu status in gastric cancer tissues. Up to date, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are the most frequently performed. A high concordance rate has been confirmed between these 2 techniques in immunohistochemical score 3+ or 1+/0 cases.8,9 However, discrepancy has been reported between IHC and FISH in gastric cancer cases scored 2+. To the best of our knowledge, data on HER2/neu status in all IHC-equivocal samples are still scare in China. In this study, FISH and IHC detection for HER2/neu were both performed in a consecutive sample of Chinese cases with gastric cancer, which were all equivocal for HER2/neu protein expression. The concordance between FISH and IHC was further investigated.
PATIENTS AND METHODS Patients From January 2013 to March 2014, all the gastric cancer cases scored IHC 2+ diagnosed at the Department of Pathology, the First Affiliated Hospital of Zhejiang University, Hangzhou, China, were included in our research work. All the patients had undergone either total or partial gastrectomy for gastric or gastroesophageal
Volume 00, Number 00, ’’ 2015
www.appliedimmunohist.com |
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
1
Liu et al
Appl Immunohistochem Mol Morphol
junction adenocarcinoma. Patients with missing data on the tumor characteristics were excluded. The remaining 122 cases were considered in the analyses. This research was approved by the ethics committee of the First Affiliated Hospital, College of Medicine, Zhejiang University. The ethics committee waived the need for consent as the data were analyzed anonymously.
IHC HER2/neu status was examined using 10% formalin-fixed paraffin-embedded tissues. Automated IHC of HER2/neu (4B5; Ventana Medical Systems, Tucson, AZ) was performed on 4-mm-thick tissue sections using an automated slide stainer, the Ventana BenchMark XT (Ventana Medical Systems). The scoring scheme of the ToGA study was used for IHC scoring.10,11 Briefly, 0, no staining or membranous reactivity in
HER2 Gene Amplification by Fluorescence In Situ Hybridization (FISH) Compared With Immunohistochemistry (IHC) in 122 Equivocal Gastric Cancer Cases Xiaoyan Liu, MSc, Xiaoling Wang, PhD, Bo Wang, MSc, Guoping Ren, MSc, and Wei Ding, BSc
Objective: To determine the frequency of HER2/neu amplification and the relationship between HER2/neu expression and clinicopathologic features in gastric cancers scored immunohistochemistry (IHC) 2+. Methods: A total of 122 gastric cancer cases scored IHC 2+ were retrospectively analyzed for HER2 amplification by fluorescence in situ hybridization (FISH). The correlation between HER2/neu expression and clinicopathologic features was analyzed. Results: HER2/neu gene was amplified in 17 out of the 122 gastric cancer samples. The concordance rate between IHC and FISH was 13.9%. HER2/neu status was correlated with the age of patients (P < 0.05). Polysomy of CEP17 was demonstrated in 46 cases, 11 of which (23.91%) were amplified for HER2/neu. Within the subgroups, a correlation between CEP17 polysomy and the depth of invasion was observed (P < 0.05). Conclusions: The results highlight the necessity of FISH test for further categorization when gastric cancer cases are scored 2+ by IHC. The value of HER2/neu for a potential role as a negative prognostic factor in the equivocal gastric cancer cases is limited. Key Words: gastric cancer, fluorescence in situ hybridization, HER2/neu (Appl Immunohistochem Mol Morphol 2015;00:000–000)
H
ER2/neu gene (also known as C-erbB-2 gene) is a member of the type-I growth factor receptor family.1 It is located on the long arm of chromosome 17, encoding a 185 kD transmembrane glycoprotein.1 Intracellular signaling and activation of genes controlling cell growth Received for publication November 23, 2014; accepted April 10, 2015. From the Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China. X.L. and X.W. contributed equally. The authors declare no conflict of interest. Reprints: Bo Wang, MSc, Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79# Qingchun Road, Hangzhou, Zhejiang 310003, China (e-mail: wangbo19800623@ sohu.com). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
Appl Immunohistochem Mol Morphol
can be triggered by the HER2/neu oncoprotein. The activation of HER2/neu is also linked with shortened survival, enhanced aggressiveness, and other poor prognostic factors.2 HER2/neu plays an important role in the development of certain solid human tumors. HER2 amplification and overexpression have been proved to be correlated with the pathogenesis of several human cancers, of which breast cancer is the most well defined.3–5 Clinical trials demonstrated that the subset of patients with HER2/neu overexpression could benefit from trastuzumab, a recombinant humanized anti-HER2/neu monoclonal antibody, in advanced and metastatic breast cancer.6 Moreover, the clinical benefit of trastuzumab in patients with inoperable or metastatic advanced gastric or gastroesophageal junction cancer characterized by HER2/ neu positive was also shown in the Trastuzumab for Gastric Cancer (ToGA) study.7 Thus the accurate evaluation on HER2/neu gene status is the first step. A wide variety of techniques has been introduced into the test of the HER2/neu status in gastric cancer tissues. Up to date, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are the most frequently performed. A high concordance rate has been confirmed between these 2 techniques in immunohistochemical score 3+ or 1+/0 cases.8,9 However, discrepancy has been reported between IHC and FISH in gastric cancer cases scored 2+. To the best of our knowledge, data on HER2/neu status in all IHC-equivocal samples are still scare in China. In this study, FISH and IHC detection for HER2/neu were both performed in a consecutive sample of Chinese cases with gastric cancer, which were all equivocal for HER2/neu protein expression. The concordance between FISH and IHC was further investigated.
PATIENTS AND METHODS Patients From January 2013 to March 2014, all the gastric cancer cases scored IHC 2+ diagnosed at the Department of Pathology, the First Affiliated Hospital of Zhejiang University, Hangzhou, China, were included in our research work. All the patients had undergone either total or partial gastrectomy for gastric or gastroesophageal
Volume 00, Number 00, ’’ 2015
www.appliedimmunohist.com |
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
1
Liu et al
Appl Immunohistochem Mol Morphol
junction adenocarcinoma. Patients with missing data on the tumor characteristics were excluded. The remaining 122 cases were considered in the analyses. This research was approved by the ethics committee of the First Affiliated Hospital, College of Medicine, Zhejiang University. The ethics committee waived the need for consent as the data were analyzed anonymously.
IHC HER2/neu status was examined using 10% formalin-fixed paraffin-embedded tissues. Automated IHC of HER2/neu (4B5; Ventana Medical Systems, Tucson, AZ) was performed on 4-mm-thick tissue sections using an automated slide stainer, the Ventana BenchMark XT (Ventana Medical Systems). The scoring scheme of the ToGA study was used for IHC scoring.10,11 Briefly, 0, no staining or membranous reactivity in
