Comparison of liquid based cytology and histology for the evaluation of HER-2 status using immunostaining and CISH in breast carcinoma

Reliability of Estrogen Receptor and Human Epidermal Growth Factor Receptor 2 Expression on Breast Cancer Cells Stored in Cellprep® Vials

OBJECTIVE

The aim of this study was to evaluate the reliability of estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) expression levels in Cellprep® (CP).

STUDY DESIGN

We evaluated the stability of immunocytochemistry (ICC) of ER and HER2 for primary or recurrent breast cancer samples rinsed in CP vials. Samples were prepared from CP vials stored for 1-30 or 160-240 days. ER and HER2 statuses were determined after 1-30 days (26 and 25 tests, respectively) or 160-240 days (15 and 18 tests, respectively) with the same protocols as immunohistochemistry (IHC), and were compared with the corresponding surgically resected specimens.

RESULTS

ER statuses according to CP samples showed perfect agreement (1-30 days: kappa, κ = 1; 160-240 days: κ = 1). HER2 statuses also showed good agreement (1-30 days: κ = 0.79; 160-240 days: κ = 0.64), although there were more equivocal HER2 cases in CP than in the surgically resected specimens.

CONCLUSION

ER ICC in CP vials is reliable regardless of the preservation period. HER2 ICC in CP has more equivocal cases than HER2 IHC in surgically resected specimens. Both improvement of the immunostaining protocol and further validation study of in situ hybridization are indispensable for the practical application of ICC in CP.

RefCNV: Identification of Gene-Based Copy Number Variants Using Whole Exome Sequencing

With rapid advances in DNA sequencing technologies, whole exome sequencing (WES) has become a popular approach for detecting somatic mutations in oncology studies. The initial intent of WES was to characterize single nucleotide variants, but it was observed that the number of sequencing reads that mapped to a genomic region correlated with the DNA copy number variants (CNVs). We propose a method RefCNV that uses a reference set to estimate the distribution of the coverage for each exon. The construction of the reference set includes an evaluation of the sources of variability in the coverage distribution. We observed that the processing steps had an impact on the coverage distribution. For each exon, we compared the observed coverage with the expected normal coverage. Thresholds for determining CNVs were selected to control the false-positive error rate. RefCNV prediction correlated significantly (r = 0.96-0.86) with CNV measured by digital polymerase chain reaction for MET (7q31), EGFR (7p12), or ERBB2 (17q12) in 13 tumor cell lines. The genome-wide CNV analysis showed a good overall correlation (Spearman's coefficient = 0.82) between RefCNV estimation and publicly available CNV data in Cancer Cell Line Encyclopedia. RefCNV also showed better performance than three other CNV estimation methods in genome-wide CNV analysis.

HER 2 immunohistochemistry for breast cancer cell blocks can be used in the same way as that used for histological specimens

Background

Human epidermal growth factor receptor 2 (HER2) testing of samples from recurrent or metastatic breast cancer is recommended by the 2013 update of the American Society of Clinical Oncology/College of American Pathologists guidelines. Although cytological analysis can be applied to several types of metastatic lesions, the practical method for HER2 testing of cytological specimens is yet to be resolved. We conducted immunohistochemical (IHC) staining for HER2 in breast cancer cell blocks (CBs) and compared the results with those from the corresponding histological specimens. In cases of discrepancy between the two types of specimen, the bright‐field HER2 dual in situ hybridization (DISH) assay was performed.

Methods

CBs were prepared from 54 surgically excised breast cancers. The cells were fixed in 10% buffered formalin and embedded in paraffin. A Ventana BenchMark ULTRA (Roche Diagnostics) with anti‐HER‐2/neu (4B5) rabbit monoclonal primary antibody and INFORM HER2/neu Dual ISH DNA Probe Cocktail was used for the assays.

Results

Successful results were obtained in 52 of 54 CBs. Forty cases showed agreement between CBs and the histological specimens. No discrepancy was observed between the two types of specimens in cases where HER2 expression was positive. IHC results of CB in 12 discrepant cases were HER2 intermediate or negative. The DISH results of 11 of these cases were negative.

Conclusion

IHC staining of HER2 for breast cancer CBs can be used in the same way as that used for histological specimens, although the number of equivocal cases in CBs is greater than that in histological specimens. Diagn. Cytopathol. 2016;44:274–279. © 2016 The Authors Diagnostic Cytopathology Published by Wiley Periodicals, Inc.

Bright-field HER2 dual in situ hybridization (DISH) assay on breast cancer cell blocks: a comparative study with histological sections

BACKGROUND

HER2 testing for samples from recurrent or metastatic disease is recommended by the 2013 update of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines and cytological analysis can be applied to several types of metastatic lesions. However, the practical method to assess the HER2 testing of breast cancer cytology specimens has yet to be resolved. Therefore, we conducted the bright-field HER2 dual in situ hybridization (DISH) assay on cell blocks (CBs) prepared from breast cancer cell samples as a validation study before clinical use.

METHODS

CBs were prepared from tumor cell samples collected from 54 surgically excised breast tumors. The cells were fixed in 10 % buffered formalin for 16-28 h, and embedded in paraffin. The INFORM HER2/neu Dual ISH DNA Probe Cocktail was used for the DISH assay on the Ventana BenchMark ULTRA (Roche Diagnostics).

RESULTS

Successful results were obtained in 51 of 54 CB specimens, and the results from the CB specimens were in agreement with those from the histological sections in 48 of the 51 cases (concordance rate, 94 %; kappa, 0.846). The intraclass correlation coefficient (ICC) between the CB and histological specimens in the continuous HER2/CEP17 signal count ratio was 0.89 (95 % CI 0.81-0.93), and the Pearson's CC was 0.91 (95 % CI 0.85-0.94).

CONCLUSION

The HER2 DISH assay, utilizing 10 % buffered formalin-fixed CB, would be a reliable and ideal method to assess the HER2 gene status of breast cancer cytological specimens.

Introduction and utility of liquid-based cytology on aspiration biopsy of peripheral nodular lesions of the lung

In the present study, aspiration biopsy cytology (ABC) was used for the diagnosis of peripheral nodular lesions in the lung (PNLL), and liquid-based cytology (LBC) was carried out on the material collected to evaluate it in comparison with the conventional method (CM). The subjects comprised 130 cases that underwent computed tomography (CT)-guided ABC for PNLL. A total of 73 cases received a tumor resection, with a diagnosis based on the pathology, while 57 cases were followed up, as the tumor showed no change on the radiological examinations. Biopsy samples from these patients and lavage fluid from the aspiration needles were used for analysis. Cellular material was obtained by centrifugation of the lavage fluid, and samples were prepared by two methods, direct smearing and LBC according to the ThinPrep method. The samples were categorized into three diagnoses: i) Benign, ii) suspicion of malignancy and iii) malignant. Appropriate samples were collected in 72% of cases by LBC, but only in 36% of cases by the CM. There was no marked difference in cellular images between the two methods, with the exception of a few specific cases. LBC on its own provided sensitivity at 68%, specificity at 61% and accuracy at 65%, while a combination of LBC and biopsy markedly improved these figures to 94, 81 and 84%, respectively. The introduction of LBC is considered useful for the cytopathological diagnosis of PNLL by CT-guided ABC. LBC enables the examination of appropriate samples rich in cellular components and supports a biopsy-based diagnosis. A combination of these two methods provides even higher diagnostic accuracy, and LBC is considered an excellent method to evaluate these pathological samples.

Assessment of Her-2/neu status using immunocytochemistry and fluorescence in situ hybridization on fine-needle aspiration cytology smears: experience from a tertiary care centre in India

Breast carcinoma shows amplification/overexpression of Her-2/neu in ∼20-30% of cases. The determination of Her-2/neu expression accurately is vital in clinical practice as it has significant predictive value and eligibility for anti Her-2/neu therapy. Amplification and overexpression of Her-2/neu gene is traditionally identified by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) on tissue sections; only a few studies have evaluated feasibility of these techniques on cytological smears. One hundred cases of breast cancer with fine-needle aspiration cytology (FNAC) samples and corresponding surgically resected specimen were selected. Immunocytochemistry (ICC) and FISH for Her-2/neu was done on FNA smears, whereas IHC was performed on corresponding tissue sections. Diagnostic accuracy of ICC was 99% when compared with IHC. Comparison of FISH results with IHC showed 100% concordance. Unlike many centers in West, FNAC is still routinely performed in developing countries like India where vast majority of breast cancer cases present as palpable lumps. The high rates of accuracy of ICC and FISH for Her-2/neu detection can make FNAC a relevant first line of investigation as a cost effective model with a rapid turn-around time, providing complete information necessary for initial management of breast cancer patients.

Chromogenic in situ hybridization compared with other approaches to evaluate HER2/neu status in breast carcinomas

Human epidermal growth factor receptor 2 (HER2) has been evaluated in breast cancer patients to identify those most likely to benefit from herceptin-targeted therapy. HER2 amplification, detected in 20-30% of invasive breast tumors, is associated with reduced survival and metastasis. The most frequently used technique for evaluating HER2 protein status as a routine procedure is immunohistochemistry (IHC). HER2 copy number alterations have also been evaluated by fluorescence in situ hybridization (FISH) in moderate immunoexpression (IHC 2+) cases. An alternative procedure to evaluate gene amplification is chromogenic in situ hybridization (CISH), which has some advantages over FISH, including the correlation between HER2 status and morphological features. Other methodologies have also been used, such as silver-enhanced in situ hybridization (SISH) and quantitative real-time RT-PCR, to determine the number of HER2 gene copies and expression, respectively. Here we will present a short and comprehensive review of the current advances concerning HER2 evaluation in human breast cancer.

Testing for her2 in breast cancer: current pathology challenges faced in Canada

This review is designed to highlight several key challenges in the diagnosis of human epidermal growth factor receptor 2 (her2)-positive breast cancer currently faced by pathologists in Canada: Pre-analysis issues affecting the accuracy of her2 testing in non-excision sample types: core-needle biopsies, effusion samples, fine-needle aspirates, and bone metastasesher2 testing of core-needle biopsies compared with surgical specimensCriteria for retesting her2 status upon disease recurrenceLiterature searches for each topic were carried out using the medline, Embase, International Pharmaceutical Abstracts, and biosis databases. In addition, the congress databases of the American Society of Clinical Oncology (2005-2011) and the San Antonio Breast Cancer Symposium (2007-2011) were searched for relevant abstracts.All authors are expert breast pathologists with extensive experience of her2 testing, and several participated in the development of Canadian her2 testing guidelines. For each topic, the authors present an evaluation of the current data available for the guidance of pathology practice, with recommendations for the optimization or improvement of her2 testing practice.

Detection of SYT and EWS gene rearrangements by dual-color break-apart CISH in liquid-based cytology samples of synovial sarcoma and Ewing sarcoma/primitive neuroectodermal tumor

To improve cytologic diagnostic accuracy for translocation-associated sarcomas, we explored dual-color break-apart (dc) chromogenic in situ hybridization (CISH) on liquid-based cytology (LBC) samples of 2 prototypic sarcomas: synovial sarcoma (SS) and Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). LBC samples of 10 cases of SS and 9 cases of ES/PNET were subjected to dc-CISH using probes for the specifically rearranged genes in each tumor entity: SYT in SS and EWS in ES/PNET. Rearranged SYT was successfully detected in all SSs but not in any ES/PNETs. In contrast, EWS rearrangement was identified in all ES/PNETs but not in any SSs. These results were validated by dc-fluorescence in situ hybridization and reverse transcription-polymerase chain reaction. dc-CISH on LBC samples is a reliable modality to detect gene rearrangements in sarcomas. This system has a clear advantage over other methods, enabling simultaneous visualization of the genetic abnormality and well-preserved, nonoverlapping cytomorphologic features with clear background under bright-field microscope.

Site-specifically conjugated anti-HER2 Affibody molecules as one-step reagents for target expression analyses on cells and xenograft samples

Affibody molecules are a class of small and robust affinity proteins that can be generated to interact with a variety of antigens, thus having the potential to provide useful tools for biotechnological research and diagnostic applications. In this study, we have investigated Affibody-based reagents interacting specifically with the tyrosine kinase receptor HER2. A head-to-tail dimeric construct was site-specifically conjugated with different fluorescent and enzymatic groups resulting in reagents that were used for detection and quantification. The amount of cell surface expressed HER2 on eleven (11) well characterized cell lines was quantified relative to each other by flow cytometry and shown to correlate well with results from parallel analyses of HER2 mRNA levels measured by real-time PCR. Further, immunofluorescence microscopy studies of the cell lines and immunohistochemical analyses of cryosections of HER2 expressing SKOV-3 xenografts showed strong staining of the plasma membrane of tumor cells with little background staining. Full-length HER2 protein could also be efficiently recovered from a cell extract by an immunoprecipitation procedure, using an Affibody ligand-based resin. These novel non-IgG derived reagents could be used to detect and quantify HER2 expression. By adapting the methods for use with Affibody molecules binding to other cell surface receptors, it is anticipated that also these receptors can be detected and quantified in a similar manner.

Chromogenic In Situ Hybridization to Detect HER‐2/ neu Gene Amplification in Histological and ThinPrep ® ‐Processed Breast Cancer Fine‐Needle Aspirates: A Sensitive and Practical Method in the Trastuzumab Era

The increasing evidence of trastuzumab efficacy in breast cancer (BC) patients means that an accurate and reproducible evaluation of HER-2 statusis of paramount importance in histological and in cytological samples. Currently, the two main methods used to analyze HER-2 amplification or overexpression are fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). Although the two methods are strongly correlated for histological tissue, the evaluation of tumor morphology through FISH may be difficult and fluorescence fades quickly. These limitations can be overcome by chromogenic in situ hybridization (CISH), which can visualize the amplification product along with morphological features. In view of this, in the present study, we analyzed the usefulness of CISH on formalin-fixed, paraffin-embedded (FFPE) BC specimens and investigated whether CISH can be a valid technique in the determination of HER-2 status for fine-needle aspirates (FNAs) processed by liquid-based cytology. The results we obtained in a retrospective series of 111 FFPE BC specimens demonstrated good concordance between CISH and IHC and between CISH and FISH. The former concordance was comparable with that observed between FISH and IHC. When CISH was applied to a prospective series of 53 FNAs, from surgically removed BC, our data showed evidence of a higher concordance of results between liquid-based cytology and the companion FFPE tissues using CISH rather than HercepTesttrade mark. Therefore, CISH analysis, which is avaluable and reproducible alternative to FISH for selecting breast cancer patients for trastuzumab therapy, can lower false-positive immunocytochemistry findings in ThinPrep-processed FNAs.