Performance of chromogenic in situ hybridization on testing HER2 Status in breast carcinomas with chromosome 17 polysomy and equivocal (2+) herceptest results: a study of two institutions using the conventional and new ASCO/CAP scoring criteria

Thioredoxin-interacting protein is an independent risk stratifier for breast ductal carcinoma in situ

Current clinicopathological parameters are useful predictors of breast ductal carcinoma in situ behavior, but they are insufficient to define high-risk patients for disease progression precisely. Thioredoxin-interacting protein (TXNIP) is a key player of oxidative stress. This study aims to evaluate the role of TXNIP as a predictor of ductal carcinoma in situ progression. Tissue microarrays from 776 pure ductal carcinoma in situ and 239 mixed ductal carcinoma in situ and invasive tumors were constructed. All patients were treated at a single institution with a long-term follow-up and TXNIP expression was assessed using immunohistochemistry. TXNIP expression was investigated in terms of associations with clinicopathological and molecular features and patient outcome. Loss/reduced cytoplasmic expression of TXNIP was associated with features of aggressiveness including high nuclear grade (p = 1.6 × 10^-5), presence of comedo necrosis (p = 0.001), and estrogen receptor negative (ER-)/HER2- ductal carcinoma in situ (p = 4.6 × 10^-5). Univariate analysis showed an inverse association between TXNIP expression and outcome in terms of shorter local recurrence-free survival (p = 0.009). Multivariable analyses showed that independent predictors of ductal carcinoma in situ recurrence were low TXNIP expression (p = 0.005, HR = 0.51, and 95% CI: 0.32-0.81), larger ductal carcinoma in situ size, and high nuclear grade. TXNIP functions as a tumor suppressor gene with loss of its expression associated with ductal carcinoma in situ recurrence. TXNIP can be used as a potentially useful marker in prognostic stratification of ductal carcinoma in situ for management decisions.

Prolyl-4-hydroxylase Α subunit 2 (P4HA2) expression is a predictor of poor outcome in breast ductal carcinoma in situ (DCIS)

Background

Extracellular matrix (ECM) plays a crucial role in tumour behaviour. Prolyl-4-hydroxlase-A2 (P4HA2) is a key enzyme in ECM remodelling. This study aims to evaluate the prognostic significance of P4HA2 in breast ductal carcinoma in situ (DCIS).

Methods

P4HA2 expression was assessed immunohistochemically in malignant cells and surrounding stroma of a large DCIS cohort comprising 481 pure DCIS and 196 mixed DCIS and invasive carcinomas. Outcome analysis was evaluated using local recurrence free interval (LRFI).

Results

High P4HA2 expression was detected in malignant cells of half of pure DCIS whereas its expression in stroma was seen in 25% of cases. Higher P4HA2 expression was observed in mixed DCIS cases compared to pure DCIS both in tumour cells and in stroma. High P4HA2 was associated with features of high risk DCIS including younger age, higher grade, comedo necrosis, triple negative and HER2-positive phenotypes. Interaction between P4HA2 and radiotherapy was also observed regarding the outcome. High P4HA2 expression was an independent prognostic factor in predicting shorter LRFI.

Conclusion

P4HA2 plays a role in DCIS progression and can potentially be used to predict DCIS outcome. Incorporation of P4HA2 with other clinicopathological parameters could refine DCIS risk stratification that can potentially guide management decisions.

Comparative Performance of Breast Cancer Human Epidermal Growth Factor Receptor 2 Fluorescence In Situ Hybridization and Brightfield In Situ Hybridization on College of American Pathologists Proficiency Tests

CONTEXT.—

Fluorescence in situ hybridization (FISH) and brightfield in situ hybridization (ISH) are 2 clinically approved laboratory methods for detecting ERBB2 (HER2) amplification in breast cancer.

OBJECTIVE.—

To compare the performance of FISH and brightfield ISH on proficiency testing administered by the College of American Pathologists Laboratory Accreditation Program.

DESIGN.—

Retrospective review was performed on 70 tissue core samples in 7 separate proficiency testing surveys conducted between 2009 and 2013.

RESULTS.—

The samples included 13 consensus-amplified tissue cores, 53 consensus-nonamplified cores, and 4 cores that did not reach consensus for FISH and/or brightfield ISH. There were 2552 individual responses for FISH and 1871 individual responses for brightfield ISH. Consensus response rates were comparable for FISH (2474 of 2524; 98.0%) and brightfield ISH (2135 of 2189; 97.5%). The FISH analysis yielded an average HER2 copy number per cell that was significantly higher (by 2.86; P = .02) compared with brightfield ISH for amplified cores. For nonamplified cores, FISH yielded slightly, but not significantly, higher (by 0.17; P = .10) HER2 copy numbers per cell. There was no significant difference in the average HER2 to control ratio for either consensus-amplified or consensus-nonamplified cores. Participants reported "unable to analyze" more frequently for brightfield ISH (244 of 2453; 9.9%) than they did for FISH (160 of 2684; 6.0%).

CONCLUSIONS.—

Our study indicates a high concordance rate in proficiency testing surveys, with some significant differences noted in the technical performance of these assays. In borderline cases, updated American Society of Clinical Oncology/College of American Pathologists cutoff thresholds that place greater emphasis on HER2 copy number per cell could accentuate those differences between FISH and brightfield ISH.

Genomic Copy Number Analysis of HER2-Equivocal Breast Cancers

OBJECTIVES

Guidelines for HER2 testing define an equivocal range for HER2 using two approved testing methods, immunohistochemistry (IHC) and in situ hybridization (ISH). We investigated genome-wide copy number alterations in this subgroup.

METHODS

Ten breast cancers with equivocal HER2 status by both IHC and ISH were analyzed by single-nucleotide polymorphism cytogenomic microarray (SNP array). DNA ploidy analysis by flow cytometry was performed on nine cases with sufficient material remaining.

RESULTS

SNP array analysis showed uniform gain of chromosome 17 (polysomy) in one case and segmental copy number gains encompassing HER2 and the centromere in five other cases. Flow cytometry revealed hyperdiploidy in six cases, all but one of which also had HER2 gains on SNP array. Although there was no evidence of HER2 amplification by SNP array, six cases showed amplification of other genomic regions, including known oncogenes in four cases.

CONCLUSIONS

A combination of hyperdiploidy and segmental copy number gains contributes to HER2 ISH-equivocal results in most breast cancers. Cases in which HER2 copy number gain is not corroborated by genomic analysis suggest the presence of other contributing variables influencing ISH results. Genomic copy number analysis also implicates non-HER2 oncogenic drivers in many cases that are HER2 equivocal.

Recommendations for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer to improve the accuracy of HER2 testing and its utility as a predictive marker in invasive breast cancer.

METHODS

ASCO/CAP convened an Update Committee that included coauthors of the 2007 guideline to conduct a systematic literature review and update recommendations for optimal HER2 testing.

RESULTS

The Update Committee identified criteria and areas requiring clarification to improve the accuracy of HER2 testing by immunohistochemistry (IHC) or in situ hybridization (ISH). The guideline was reviewed and approved by both organizations.

RECOMMENDATIONS

The Update Committee recommends that HER2 status (HER2 negative or positive) be determined in all patients with invasive (early stage or recurrence) breast cancer on the basis of one or more HER2 test results (negative, equivocal, or positive). Testing criteria define HER2-positive status when (on observing within an area of tumor that amounts to >10% of contiguous and homogeneous tumor cells) there is evidence of protein overexpression (IHC) or gene amplification (HER2 copy number or HER2/CEP17 ratio by ISH based on counting at least 20 cells within the area). If results are equivocal (revised criteria), reflex testing should be performed using an alternative assay (IHC or ISH). Repeat testing should be considered if results seem discordant with other histopathologic findings. Laboratories should demonstrate high concordance with a validated HER2 test on a sufficiently large and representative set of specimens. Testing must be performed in a laboratory accredited by CAP or another accrediting entity. The Update Committee urges providers and health systems to cooperate to ensure the highest quality testing.

Recommendations for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer to improve the accuracy of HER2 testing and its utility as a predictive marker in invasive breast cancer.

METHODS

ASCO/CAP convened an Update Committee that included coauthors of the 2007 guideline to conduct a systematic literature review and update recommendations for optimal HER2 testing.

RESULTS

The Update Committee identified criteria and areas requiring clarification to improve the accuracy of HER2 testing by immunohistochemistry (IHC) or in situ hybridization (ISH). The guideline was reviewed and approved by both organizations.

RECOMMENDATIONS

The Update Committee recommends that HER2 status (HER2 negative or positive) be determined in all patients with invasive (early stage or recurrence) breast cancer on the basis of one or more HER2 test results (negative, equivocal, or positive). Testing criteria define HER2-positive status when (on observing within an area of tumor that amounts to > 10% of contiguous and homogeneous tumor cells) there is evidence of protein overexpression (IHC) or gene amplification (HER2 copy number or HER2/CEP17 ratio by ISH based on counting at least 20 cells within the area). If results are equivocal (revised criteria), reflex testing should be performed using an alternative assay (IHC or ISH). Repeat testing should be considered if results seem discordant with other histopathologic findings. Laboratories should demonstrate high concordance with a validated HER2 test on a sufficiently large and representative set of specimens. Testing must be performed in a laboratory accredited by CAP or another accrediting entity. The Update Committee urges providers and health systems to cooperate to ensure the highest quality testing. This guideline was developed through a collaboration between the American Society of Clinical Oncology and the College of American Pathologists and has been published jointly by invitation and consent in both Journal of Clinical Oncology and the Archives of Pathology & Laboratory Medicine.

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.

Evaluation of dual immunohistochemistry and chromogenic in situ hybridization for HER2 on a single section

The evaluation of HER2 status in invasive breast carcinoma can be performed by multiple methods. We assessed the feasibility of performing 2 of these, chromogenic in situ hybridization (CISH) and immunohistochemical staining, on single tissue sections of breast carcinoma. During assay development, sequential performance of immunohistochemical staining after CISH resulted in weaker HER2 expression than that obtained when immunohistochemical staining was performed alone; this was ameliorated by increased antibody incubation time. Performance of both techniques in a combined/hybrid protocol resulted in HER2 protein expression and gene signals identical to those produced by the individual techniques performed alone. Prospective validation of these dual staining protocols in 31 cases of breast carcinoma resulted in 100% concordance with results of CISH when performed alone, but was still associated with a reduced immunohistochemical signal in some cases. Although further testing is needed, we conclude that performance of both immunohistochemical staining and CISH on a single section is possible and could allow for direct "cell-by-cell" comparison of HER2 signals and potentially offer a more economical and real-time method for ongoing validation of HER2 testing.

Traditional molecular markers and response to adjuvant endocrine or trastuzumab-based therapies

PURPOSE OF REVIEW

The accurate assessment of traditional molecular markers is essential to inform the choice of the adjuvant systemic treatments for patients with breast cancer. Extensive research efforts have been made to explore whether it is also possible to predict the actual response to the different therapeutic options based on the expression of these markers.

RECENT FINDINGS

Endocrine responsiveness of breast cancer has been eventually defined according to the expression of estrogen receptors in at least 1% of invasive tumor cells. The quantitative evaluation of estrogen receptors, progesterone receptors (PgR) and Ki-67 labeling index may help in selecting patients with estrogen receptor-positive and HER2-negative tumors who can be spared or may benefit from the addition of chemotherapy to endocrine therapy. Guideline recommendations for an optimal testing of estrogen receptors and PgR have been issued to assist pathologists in the accurate assessment of these markers. Progress has also been made in the identification of candidate patients to HER2-targeted therapies and in the prediction of response to trastuzumab.

SUMMARY

Traditional molecular markers play a major role in the selection of candidate patients to systemic interventions, but they are of limited value in predicting their actual response to the different treatments, especially when the markers are evaluated individually.

Determination of HER-2 status on FNAC material from breast carcinomas using in situ hybridization with dual chromogen visualization with silver enhancement (dual SISH)

During the last years, HER-2 status kits and protocols for chromogen visualization of hybridization signals have come on the market. The first generation using chromogen visualization used single color probes. The second generation, now emerging on the market, uses dual chromogen visualization. The aim of this study has been to test a new dual color chromogen kit (Ventana INFORM HER2 Dual Colour ISH Roche^®) and compare the results with our in-house method(s). The material consisted primarily of cytological material from invasive breast carcinomas in 49 women. Dual SISH was done on all 49 cytological and histological specimens. The histological specimens were treated according to the manufacturer’s recommendations. The procedure was modified in several steps in order to adapt it to the cytological material. Hybridization failed in two cytological specimens. Dual SISH showed concordant results on cytological and histological material as to amplified/not amplified. The included cases had the same HER-2 expression in the invasive and the in situ components on histology. Four IDC showed HER-2 amplification (8.5%). Polysomy was found in two cases. All dual SISH results except for one concurred with the results of the in-house method(s) (1/47=2.1%). The dual SISH is suitable for cytological examination of HER-2 status. The protocol must be optimized for cytological material.

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.