Evaluation of the prognostic significance of HER family mRNA expression in high-risk early breast cancer: a Hellenic Cooperative Oncology Group (HeCOG) validation study

Angelos Koutras,Christina Magkou,George Fountzilas,Konstantine T Kalogeras,Ralph M Wirtz,Elke Veltrup,Eleni Timotheadou,Gerasimos Aravantinos,Zoi Alexopoulou,Mattheos Bobos,Dimitrios Pectasides,Pavlos Papakostas,Dimitrios Bafaloukos,Christos Christodoulou,Flora Zagouri,Nikolaos Pisanidis,Haralambos P Kalofonos,George Pentheroudakis,Helen Gogas

doi:10.1186/s12967-015-0530-0

Abstract

BackgroundThe aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the HER family genes in early breast cancer, as a validation analysis of another previously published HeCOG study.MethodsRNA was extracted from 663 formalin-fixed paraffin-embedded (FFPE) tumor tissue samples of high-risk early breast cancer patients enrolled in the randomized HE10/00 trial. Relative mRNA expression of all four HER family members was assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR).ResultsIn compliance with our previous study, the overall agreement between qRT-PCR and IHC/FISH for HER2 status determination was good (69%). Likewise, the overall concordance between qRT-PCR and IHC for EGFR status was high (81%). In line with our previously reported data, we demonstrated a positive association between HER2 and HER3 mRNA expression. Similarly, mRNA expression of HER3 and HER4 was positively associated with each other and negatively associated with EGFR. Regarding relationships with clinico-pathological parameters, our findings are also in agreement with our previous results. Generally, increased EGFR and HER2 mRNA expression was related to unfavorable, whereas high HER3 and HER4 mRNA expression was associated with favorable clinico-pathological parameters. In univariate analysis, no significant association between EGFR, HER2 and HER3 mRNA expression and overall survival (OS) or disease-free survival (DFS) was demonstrated. However, high EGFR protein expression was associated with significantly shorter OS (log-rank, p = 0.015). In compliance with our previously published data, increased HER4 mRNA expression had a significantly favorable prognostic value in terms of OS (p = 0.044) and DFS (p = 0.047). In multivariate analysis, among all HER receptors, only EGFR protein expression was found to affect OS (Wald’s p = 0.028) and DFS (p = 0.015) independently. Concerning the combined expression of all four HER family receptors, the combination of high EGFR, high HER2, low HER3 and low HER4 mRNA expression was associated with a trend for shorter OS (log-rank, p = 0.065) and significantly worse DFS (p = 0.033), compared with all other co-expression profiles.ConclusionsThese data indicate that qRT-PCR may represent a valid alternative method for evaluating the expression of HER family members in FFPE breast carcinoma tissue samples.Trial registrationAustralian New Zealand Clinical Trials Registry ACTRN12609001036202

Highlights

The aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the human epidermal growth factor receptor (HER) family genes in early breast cancer, as a validation analysis of another previously published Hellenic Cooperative Oncology Group (HeCOG) study
In order to validate the above findings in the current study, we evaluated the prognostic ability of HER family messenger ribonucleic acid (RNA) (mRNA) expression using qRT-polymerase chain reaction (PCR), in a larger series of high-risk patients with early breast cancer
The cohort of patients used in the current analysis included cases with more aggressive characteristics, such as higher histological grade, higher number of positive nodes and tumor size, with higher histological grade being found to be associated with HER2 status (66% in HER2-positive vs. 46% in HER2-negative patients, p < 0.001)

Summary

Introduction

The aim of the study was to evaluate the prognostic ability of the transcriptional profiling of the HER family genes in early breast cancer, as a validation analysis of another previously published HeCOG study. The HER family constitutes a promising area for the development of targeted treatments in patients with breast cancer and considerable therapeutic progress has already been achieved. The evaluation of all HER family members as a whole is considered important. Overexpression and/or amplification of the HER2 receptor occurs in 15–30% of breast cancer cases and is associated with aggressive course of the disease and unfavorable clinical outcome [2]. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) represents an alternative test for the determination of HER2 status. QRT-PCR does not necessitate experienced pathologists to interpret the results and is associated with reproducible and quantitative findings. Previous reports have demonstrated that the qRT-PCR can be applied in archival formalin-fixed paraffin-embedded (FFPE) tissues [6]

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