Dual-colour chromogenic in situ hybridization for testing of HER-2 oncogene amplification in archival breast tumours

Chromogenic in situ hybridization (CISH), which uses an enzymatic reaction to detect the hybridized DNA probe, is a new alternative to fluorescence in situ hybridization (FISH) for the assessment of HER-2 oncogene amplification status in breast cancer. The main advantage of CISH over FISH is the use of bright-field microscopy, which is rapid and allows the histopathological evaluation of tumour tissue sections. The main disadvantage of CISH has been the use of a single probe, thereby making it necessary to hybridize the control probe (chromosome 17 centromere) on an adjacent tissue section. The present paper presents an efficient protocol for dual-colour CISH (dc-CISH) based on the co-hybridization of probes to the HER-2 oncogene and chromosome 17 centromere. The probes were detected sequentially with antibodies to digoxigenin and biotin and with secondary antibody polymers labelled with horseradish peroxidase and alkaline phosphatase. The peroxidase reaction was visualized with tetramethyl benzidine (green reaction product) and the alkaline phosphatase reaction with New Fuchsin (red reaction product). The accuracy of the method was verified by comparing the results for four cell lines and 40 tumour samples with those obtained using FISH (Vysis Inc.). The results of FISH and dc-CISH showed high concordance (91%, Kappa coefficient = 0.82). It is concluded that dual-colour CISH, which is a new alternative to FISH enables the assessment of copy number ratio (HER-2/17 centromere) in conjunction with proper histopathological evaluation and the ease of bright-field microscopy.     

Evaluation of HER2 gene amplification in invasive breast cancer using a dual‐color chromogenic in situ hybridization (dual CISH)

Fluorescence in situ hybridization (FISH) assay is considered the ‘gold standard’ for evaluation of HER2/neu (HER2) gene status, however, it is difficult to recognize morphologic features of tumors using fluorescence microscopy. Thus, chromogenic in situ hybridization (CISH) has been proposed as an alternative method to evaluate HER2 gene amplification. Here, we examined the dual color CISH (dual CISH) method which provides information regarding the copy number of the HER2 gene and chromosome 17 centromere from a single slide. We examined 40 cases of invasive ductal carcinomas of the breast that were resected surgically. HER2 gene status was assessed with FISH (Abbott) and dual CISH (Dako). HER2 gene amplification status was classified according to the guidelines of the American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP). Comparison of the cut‐off values for HER2/chromosome 17 centromere copy number ratio obtained by dual CISH and FISH showed that there was almost perfect agreement between two methods (Kappa coefficient 0.96). The results of the two commercial products were almost consistent for evaluation of HER2 gene counts on the sections. The current study proved that dual CISH is comparable with FISH for evaluating HER2 gene status.     

Chromogenic in situ hybridization (CISH) to detect HER2 gene amplification in breast and gastric cancer: Comparison with immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH)

The chromogenic in situ hybridization (CISH) assay, designed to detect the amplification of the HER2 gene in formalin‐fixed, paraffin‐embedded (FFPE) breast cancer (BC) and gastric cancer (GC) tissue specimens, was evaluated in 125 FFPE BC cases and 198 FFPE GC cases for which the HER2 status had been predetermined using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). In the 125 BC cases and the 198 gastric cases, we found a very good concordance (98.4% and 99.0%, respectively) between CISH and FISH. In particular, we evaluated the polysomy cases, as these cases often have ambiguous treatment options in clinical practice. The polysomy of chromosome 17 was defined as the presence of three or more CEP17 signals in at least 10% of the tumor cells. In the 50 BC cases and 54 GC cases displaying chromosome 17 polysomy, the concordance between FISH and CISH was 98.0% and 98.1%, respectively. These results indicate that CISH could provide an accurate and practical alternative to FISH for the clinical diagnosis of HER2 gene amplification in FFPE BC and FFPE GC samples.     

Hybridization for human epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in-situ hybridization with a novel fully automated dual-colour silver in-situ hybridization method

García‐García E, Gómez‐Martín C, Angulo B, Conde E, Suárez‐Gauthier A, Adrados M, Perna C, Rodríguez‐Peralto J L, Hidalgo M & López‐Ríos F
(2011) Histopathology 59 , 8–17 Hybridization for human epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in‐situ hybridization with a novel fully automated dual‐colour silver in‐situ hybridization method Aims: Amplification of the human epidermal growth factor receptor 2 (HER2) gene has been reported in gastric carcinoma (GC). Accordingly, trastuzumab plus chemotherapy has recently become the new standard treatment for HER2‐positive advanced GCs. The aim was to compare the alleged gold standard for hybridization [fluorescence in‐situ hybridization (FISH)] with a novel, fully automated brightfield dual‐colour silver‐enhanced in‐situ hybridization (SISH) method. Methods and results: The studies series was comprised of 166 GC samples. Additionally, tumours with discordant results obtained by FISH and SISH were analysed by real‐time quantitative polymerase chain reaction (PCR) with the LightMix kit HER‐2/neu. Of the samples, 17.5% and 21% were amplified by FISH and SISH, respectively. Heterogeneity was identified in up to 52% of cases. In 96.4% of cases, FISH showed the same results as SISH. All six discordant cases were positive by SISH and negative by FISH. On review of the FISH slides, all contradictory cases were polysomic and were confirmed to be negative for amplification by real‐time PCR. Interestingly, all ratios in this latter group were between 2.06 and 2.50, so setting the cut‐off for amplification at ≥3 resulted in perfect concordance. Conclusions: Dual‐colour SISH represents a novel method for the determination of HER2 status in GC.     

Determination of HER2 amplification in primary breast cancer using dual‐colour chromogenic in situ hybridization is comparable to fluorescence in situ hybridization: a European multicentre study involving 168 specimens

García‐Caballero T, Grabau D, Green A R, Gregory J, Schad A, Kohlwes E, Ellis I O, Watts S & Mollerup J
(2010) Histopathology 56, 472–480
Determination of HER2 amplification in primary breast cancer using dual‐colour chromogenic in situ hybridization is comparable to fluorescence in situ hybridization: a European multicentre study involving 168 specimens Aims: Fluorescence in situ hybridization (FISH) can be used to reveal several genomic imbalances relevant to proper cancer diagnosis and to the correct treatment regime. However, FISH requires expensive and advanced fluorescence microscopes in addition to expertise in fluorescence microscopy. To determine whether a newly developed dual‐colour chromogenic in situ hybridization (CISH) method is a suitable alternative to FISH, we analysed the human epidermal growth factor receptor 2 gene (HER2) amplification level of 168 breast cancer specimens using dual‐colour CISH and FISH and compared the results. Methods and results: We found 100% agreement between HER2 status determined by FISH and dual‐colour CISH. Furthermore, we observed that the time used to score slides was significantly reduced by 28% in dual‐colour CISH compared with the FISH protocol. Concordance between HER2 protein status and dual‐colour CISH or FISH was equally good with an overall agreement of 96.8%. Correlation between the HER2/centromere 17 gene ratios obtained with dual‐colour CISH and FISH was highly significant with an overall correlation coefficient (ρ) of 0.96. Conclusions: We conclude that dual‐colour CISH and bright field microscopy are excellent alternatives to FISH when analysing the HER2 status of primary breast cancer.     

乳腺癌Her2基因荧光原位杂交及其临床病理关系

目的探讨Her2基因过表达的比例及其与临床病理之间的联系。方法收集乳腺浸润型导管癌标本50例,总结其临床及病理资料,应用石蜡包埋组织切片,以EnVision两步法进行免疫组织化学染色标记ER、PR及HER2,以金菩嘉DNA探针试剂盒行荧光原位杂交检测HER2基因。结果患者平均年龄55.5岁,病理组织分级Ⅰ级11例,Ⅱ级30例,Ⅲ级9例。术后分期Ⅰ期13例,ⅡA期15例,ⅡB期13例,ⅢA期6例,ⅢB期2例,ⅢC期1例。淋巴结中位转移率6.91%。ER阳性33例,PR阳性32例,IHC法HER2阳性40例,FISH阳性33例,阴性17例。FISH法检测HER2基因与HER2蛋白过表达之间相关(P0.05),其与病理分级、术后分期、淋巴结转移率及ER、PR的表达无相关(P0.05),3例脉管内瘤栓及3例原发瘤数大于1者,FISH均为阳性。结论FISH检测HER2基因扩增和免疫组化检测HER2蛋白一致性较好,HER2基因与脉管内瘤栓及多个原发瘤有一定关系,但其作为间接预测预后的指标有待于进一步研究。     

乳腺癌组织HER2基因扩增的检测方法

目的:评价高分辨率熔体聚合酶链反应(high-resolution melt polymerase chain reaction,HRM-PCR)检测HER2基因扩增的有效性及其与荧光原位杂交(fluorescence in situ hybridization,FISH)和免疫组织化学(immunohistochemistry,IHC)检测法的一致性.方法:采用HRM-PCR法检测HER2阴性及阳性细胞株,评估检测方法的有效性;检测98例已行FISH和/或IHC的临床样本,并与FISH和IHC结果进行比较.结果:HRM-PCR检测可以有效区分HER2阴性及阳性细胞株(P<0.05),具有较好的可重复性;检测98例临床样本显示,阴性和阳性样本检测结果差异有统计学意义(0.18±0.14 vs 1.42±0.88,P<0.01),与IHC的一致性为80.33%(kappa=0.6,P<0.01),与FISH的一致性为87.88%(kappa=0.7,P<0.01),结论:HRM-PCR是一种可靠有效的检测HER2基因扩增的方法,与FISH和IHC均有较好的一致性.     

荧光原位杂交检测乳腺癌HER2基因状态

目的 探讨荧光原位杂交（FISH）,与免疫组织化学（IHC）染色（3＋）和（2＋）检测HER2基因状态的结果的一致性、导致两者差异的可能原因及FISH检测HER2基因状态的必要性和可行性。方法 采用PathVysion^TM探针试剂盒,以FISH方法,对28例IHC EnVision法染色分别为（3＋）、（2＋）、（1＋）和阴性（-）的乳腺癌石蜡切片标本进行HER2基因状态的检测。结果 HER2表达（3＋）的12例标本中,10例HER2基L大1扩增,其中2例为17号染色体多体,另2例无扩增的病例均为多体;IHC为（2＋）的10例标本中,7例为HER2基因扩增,其中1例为多体,另3例无扩增病例中2例为多体;IHC为（1＋）的3例标本均无HER2基因扩增,其中1例为多体;IHC（-）的3例标本均无基因扩增,其中1例为多体。结论 IHC是初步筛查HER2状态的首选方法;因IHC（2＋）与FISH检测结果差异较大,所以这类患者应做FISH确诊;IHC（3＋）存在假阳性,主要原因可能是由于17号染色体非整倍体,必要时这类患者也应做FISH。     

Comparison between immunohistochemistry and chromogenic in situ hybridization in assessing HER-2 status in breast cancer

Human epidermal growth factor receptor-2 (HER-2) is usually determined as a potential target for breast cancer therapy. The purpose of the present study was to compare chromogenic in situ hybridization (CISH) with immunohistochemistry (IHC) in determination of HER-2 status, in metastatic breast cancer patients screened for the clinical study of chemotherapy +/- herceptin. It was possible to assess both CISH and IHC in 56 cases, using CISH Detection Kit (Zymed) and HercepTest (DakoCytomation), respectively. HER-2 was amplified by CISH in 32 cases (57%) while 33 (59%) were HER-2-positive by IHC. A concordance between HER-2 status determined by CISH and IHC was noted in 43 of 56 cases (77%; P = 0.00008). Gene amplification was observed in 6/16 cases (37.5%) in IHC-negative subgroup (1+), while no amplification was observed in 5/10 cases (50%) in the IHC-positive subgroup (2+). These results suggest that there was a greater heterogeneity on the genetic level and that simple IHC classification was not sufficient. It is suggested that CISH could be considered as a useful additional method to IHC in determining HER-2 status in breast cancer patients, with a recommendation for testing not only the 2+ but also the 1+ subgroup of patients.     

Prognostic value of HER2 gene amplification detected by chromogenic in situ hybridization (CISH) in metastatic breast cancer

After so many years of research, clinical value of HER2 (Human epidermal growth factor receptor 2) is unclear. Perhaps the main reason is variability of testing methods that produce controversial results. There is a lack of studies regarding prognostic value of CISH especially in metastatic breast cancer (MBC) when risk evaluation is based on different parameters than for primary breast cancer. Aim of this study was to compare prognostic relevance of HER2 status in MBC tested by two different methods i.e. immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH).HER2 status of the same group of 107 MBC patients was determined by IHC (protein overexpression) and by CISH (gene amplification). HER2 results obtained by IHC and CISH showed significant correlation, beside the existence of discrepancies. Beside the significant correlation in two methods, there was a difference in prognostic values of compared methods during the course of metastatic disease. There was a significant difference in progression-free interval (PFI) between HER2 non-amplified and HER2 amplified cases determined by CISH, in postmenopausal subgroup and node-positive subgroup, but no significant difference for IHC stratified MBC patients. CISH seems to be accurate and more informative method than IHC regarding prognostic value of HER2 in metastatic breast cancer.     

Assessment of a HER2 scoring system for gastric cancer: results from a validation study

Aims:  Human epidermal growth factor receptor 2 (HER2) overexpression/amplification is implicated in the development of various solid tumour types. Validated methods and scoring systems for evaluating HER2 status exist in breast cancer, but not in gastric cancer. The aim was to establish a HER2 scoring system for gastric cancer to identify suitable patients for enrolment in a trial of trastuzumab (Herceptin^®) in advanced metastatic gastric cancer.
Methods and results:  Formalin-fixed paraffin-embedded gastric cancer samples were tested for HER2 status using the fluorescence in situ hybridization (FISH) pharmDx™ kit (Dako Denmark A/S). Immunohistochemistry (IHC) was performed using the HercepTest™ (Dako). Concordance between FISH and IHC was 93.5% in 168 evaluable samples. Eleven samples were scored as FISH+ but IHC− or equivocal.
Conclusions:  IHC/FISH discrepancies were attributed to basolateral membranous immunoreactivity of glandular cells resulting in incomplete membranous reactivity and/or a higher rate of tumour heterogeneity in gastric cancer compared with breast cancer. With modifications to the IHC scoring system, the HercepTest™ is considered valid for the identification of HER2+ gastric tumours for this clinical trial. Correlation of HER2 scores with clinical outcomes will be needed to determine which patients might benefit from trastuzumab therapy.     

Chromogenic in situ hybridization for Her‐2/neu‐oncogene in breast cancer: comparison of a new dual‐colour chromogenic in situ hybridization with immunohistochemistry and fluorescence in situ hybridization

Aims: Her‐2/neu testing is used as a marker for Herceptin^® therapy. The aim was to investigate new dual‐colour chromogenic in situ hybridization (CISH), in a large number of breast carcinomas (n = 205) with DNA‐specific dual‐colour probes (ZytoVision, Bremerhaven, Germany) and to compare the results with immunohistochemistry (n = 205) and fluorescence in situ hybridization (FISH) (n = 129). Methods and results: Paraffin‐embedded tissue of 205 patients was used. After immunohistochemistry with a focus on immunohistochemically uncertain cases, Her‐2/neu amplification using dual‐colour CISH (ZytoVision^®) was analysed. Validation by FISH was performed. The results were: immunohistochemistry, 27.8% with strong expression, 53.7% with uncertain overexpression and 18.5% with no expression; FISH, 25.6% amplified and 74.4% negative; CISH, 35.6% amplified, 62.9% negative and 1.5% not evaluable. Comparison of immunohistochemistry with CISH: CISH negative in 100% with immunohistochemistry 0/1+, amplified in 82.5% with immunohistochemistry 3+; 5.9% contradictory results: 4.4% immunohistochemistry 3+ and negative by CISH, 1.5% negative in immunohistochemistry but amplified by CISH; FISH (129 cases), 8.5% contradictory results to immunohistochemistry, 6.2% immunohistochemistry 3+ and negative by FISH, 2.3% negative by immunohistochemistry and amplified by FISH; comparison of CISH and FISH, 94.6% same results, 3.9% different ones, 1.6% CISH not analysable. Conclusions: CISH, using dual‐colour probes (ZytoVision^®) is as good as FISH for Her‐2/neu analysis. The few discrepant results are likely to be caused by polysomy or tumour heterogeneity.     

Simultaneous detection of HER2/neu gene amplification and protein overexpression in paraffin-embedded breast cancer

The determination of HER2/neu status in breast carcinomas has become essential for the selection of breast cancer patients for Herceptin therapy. Herceptin treatment is used in patients with metastatic breast carcinoma with HER2/neu protein overexpression detected by immunohistochemistry (IHC) or gene amplification analysed by fluorescence in situ hybridization (FISH). A multiparametric fluorescent approach based on the simultaneous detection of HER2/neu gene amplification and protein expression was established to increase the accuracy, and to improve the reproducibility, of HER2/neu diagnostics. Based on four paraffin-embedded breast cancer cell lines, a combined fluorescent immunostaining (FIHC) and FISH method was developed by using the PathVysion HER2 DNA Probe Kit (VYSIS) and the polyclonal antibody from the HercepTest (DAKO). Diagnostic applicability was documented on 215 formalin-fixed primary breast carcinomas. Criteria for immunofluorescence quantification were chosen by analogy with the FDA-approved HercepTest scoring, ranging from 0 to 3+. There was 97.7% concordance between conventional IHC and fluorescence IHC. The FISH data resulting from the multiparametric approach did not differ from conventional FISH. Breast carcinomas with HER2/neu protein overexpression and simultaneous gene amplification were detected with 100% sensitivity. In addition, five of the 215 cases (2.3%) had HER2/neu gene amplification without protein overexpression. The main advantage of this novel approach is that polysomy, aneuploidy, gene amplification, and protein content can be analysed simultaneously in the same cell.     

Optimization of trypsin treatment condition utilizing immunohistochemistry for chromogenic in situ hybridization

Chromogenic in situ hybridization (CISH) is a molecular technique used to visualize specific genes. Both heat treatment and protease treatment play important roles for the success of CISH on formalin‐fixed paraffin‐embedded (FFPE) tissue sections. In contrast to heat treatment, the optimal condition of protease treatment may vary depending on each sample. Because trypsin has a substrate specificity to cleave lysine and arginine, we hypothesized that trypsin could effectively degrade histones rich in lysine and arginine and that the removal of histones from DNA following heat treatment could improve CISH results. We selected 21 patients with lung adenocarcinoma previously known to be positive or negative for anaplastic lymphoma kinase (ALK) gene rearrangement and used FFPE tissue sections collected from these patients. Then, we assessed histone degradation among the following protease treatments; trypsin, pepsin, and proteinase K, and compared the ALK CISH results with results obtained using commercially available kits and these protease treatments. The results showed that trypsin effectively degraded histones. Additionally, compared with the other treatments, ALK CISH with trypsin treatment showed the most evaluable cells and the smallest standard deviation. Our study suggests that the degradation of histones by trypsin subsequent to heat treatment might improve CISH results.     

双色银染原位杂交与荧光原位杂交检测胃癌患者HER2基因状态

目的 比较双色银染原位杂交(DSISH)与荧光原位杂交(FISH)两种技术在胃癌HER2检测中的优缺点,评价DSISH用于胃癌患者HER2基因扩增状态检测的可行性.方法 收集2009年1月至3月在四川大学华西医院行根治性手术的原发性胃或胃食管交界处腺癌80例,行全自动免疫组织化学(IHC)染色检测HER2蛋白表达,所有标本行FISH和全自动DSISH检测HER2基因状态,比较不同检测方法之间的符合率.结果 DSISH和FISH初检均有5例失败,经重复检测后结果满意.IHC检测3+的13例中DSISH检测12例、FISH检测11例为HEB2基因扩增;IHC检测2+的6例中DSISH、FISH检测均有1例为基因扩增;IHC检测1+的18例中DSISH、FISH检测均有2例为基因扩增;IHC检测为0的43例中DSISH、FISH检测均无基因扩增.80例原位杂交病例中,仅1例检测结果不一致(DSISH有基因扩增而FISH无基因扩增),两种方法的总体符合率为98.8%(79/80,κ=0.958,P＜0.01).结论 DSISH技术用于胃癌HER2基因检测结果与FISH符合率高.DSISH与FISH检测各有优缺点,DSISH更具有可行性和实际应用价值.

Abstract：

Objective To investigate the advantages and disadvantages of dual-color silverenhanced in-situ hybridization(DSISH)and fluorescence in-situ hybridization(FISH)for determination of HER2 gene status in gastric carcinoma and to evaluate tlle feasibility of DSISH.Methods Eighty cases of primary gastric or gastroesophageal junction adenecarcinomag diagnosed and treated surgically from January to March.2009 at the West China Hospital were enrolled in the study.Automated immunohistochemistry (IHC)staining,FISH and automated DSISH were carried out to detect the HER2 status,respectively,and the concordance ofthe three techniques was then evaluated.Results DSISH and FISH failed initially,but repeated detection Was successful in 5 eases.Gene amplification was detected in 12/13 IHC 3+ cases in DSISH and in 11/13 IHC 3+ cases in FISH.In 6 IHC 2+cages, the amplification rate was both 1/6;in 18 IHC 1+cases.the amplifieation rate was both 2/18.No amplification Was observed in 43 IHC 0 cases.Only one of the 80 cases showed discrepancy.and tIlerefore the overall concordance between FISH and DSISH Wag 98.8%(κ=0.958,P＜0.01).Conclusions DSISH represents a novel approach for the determination of HER2 status in gastric carcinoma, and the overall concordance between DSISH and FISH is excellent.Despite their advantages and disadvantages.DSISH is more feasible and practical for routine application in surgical pathology.     

Detection of Her-2/neu oncogene in breast carcinoma by chromogenic in situ hybridization in cytologic specimens

Determination of Her-2/neu oncogene amplification is important in the current treatment of breast carcinoma. In addition to fluorescence in situ hybridization (FISH) and immunohistochemical stain (HercepTest), chromogenic in situ hybridization (CISH) has been shown to be a sensitive and specific method to determine the Her-2/neu status of surgical specimens. The effectiveness of CISH in detecting the Her-2/neu oncogene in cytologic specimens has not been well documented. Twenty-five cases of fine needle aspirate smears and touch imprints from infiltrating ductal carcinomas were examined. Both CISH and FISH were performed on each case using a digoxigenin-labeled Her-2 DNA probe for CISH (Zymed) and both Her-2 and chromosome 17 probes for FISH (Vysis). Sixty tumor cells were evaluated in each case. The scoring system and interpretation of CISH were as follows: (1) no amplification (<5 brown dots/nucleus), (2) amplification (>10 brown dots/nucleus), and (3) low-level amplification (5-9 brown dots/nucleus). Of the 25 cases analyzed, 23 (3 amplified and 20 nonamplified) showed similar results for both methods. Two cases were discordant. In these cases, low-level amplification was suggested by CISH but nonamplification by FISH. One of the cases can be explained by polysomy for chromosome 17 by FISH. In conclusion, our preliminary data suggest that CISH is a useful technique to determine Her-2/neu oncogene status in cytologic specimens. In a case of low-level amplification, a CISH chromosome 17 probe should be used, or FISH is recommended for confirmation.     

Prognostic value of HER2 expression in meningiomas: an immunohistochemical and fluorescence in situ hybridization study

The aggressiveness of meningiomas is unpredictable. HER2 represents a well-known prognostic factor in various tumors such as breast carcinomas. This work was designed to study HER2 protein expression and HER2 gene amplification in meningiomas and to evaluate their prognostic value. Frozen sections of 35 meningiomas were immunostained for HER2, estrogen receptor, progesterone receptor, E-cadherin, and MIB-1. Meningiomas immunostained for HER2 were further examined for the HER2 gene amplification by dual-color fluorescence in situ hybridization using probes for centromere 17 and 17q11.2-q12. Complete clinical information was obtained in all cases. The study included 15 atypical meningiomas, 3 anaplastic meningiomas, and 17 classic meningiomas. Five atypical/anaplastic meningiomas and 5 classic meningiomas of the whole 35 (28.5%) meningiomas expressed HER2 protein. This was considered as an overexpression in comparison with negative normal meninges. Fluorescence in situ hybridization demonstrated more HER2 gene copy in 4 of these 10 HER2-positive meningiomas. At equivalent histologic grading, meningiomas with HER2 overexpression exhibited similar immunohistochemical parameters of prognostic value than their HER2-negative counterparts; however, the rate of tumor recurrence was significantly higher in meningiomas with HER2 overexpression than in HER2-negative meningiomas. Conversely, HER2 amplification was not associated with recurrence. Some meningiomas exhibit HER2 protein overexpression in part induced by gene amplification. However, only HER2 overexpression could represent an independent prognostic factor in meningiomas.