The effects of under 6 hours of formalin fixation on hormone receptor and HER2 expression in invasive breast cancer: a systematic review

Unusual Patterns of HER2 Expression in Breast Cancer: Insights and Perspectives

The biomarker human epidermal growth factor receptor-2 (HER2) has represented the best example of successful targeted therapy in breast cancer patients. Based on the concept of "oncogene addiction," we have learnt how to identify patients likely benefitting from anti-HER2 agents. Since HER2 gene amplification leads to marked overexpression of the HER2 receptors on the cell membrane, immunohistochemistry with clinically validated antibodies and scoring system based on intensity and completeness of the membranous expression constitute the screening method to separate negative (score 0/1+) and positive (score 3+) carcinomas and to identify those tumours with complete yet only moderate HER2 expression (score 2+, equivocal carcinomas), which need to be investigated further in terms of gene status to confirm the presence of a loop of oncogene addiction. This process has demanded quality controls and led to recommendations by Scientific Societies, which pathologists routinely need to follow to guarantee reproducibility. In this review, we will span from the description of classical HER2 evaluation to the discussion of those scenarios in which HER2 expression is unusual and/or difficult to define. We will dissect HER2 heterogeneity, HER2 conversion from primary to relapsed/metastatic breast cancer, and we will introduce the new category of HER2-low breast carcinomas.

Accelerated Tissue Processing With Minimal Formalin Fixation Time for 9-Gauge Vacuum-Assisted Breast Biopsy Specimens

Objectives

Vacuum-assisted biopsy (VAB) of the breast seems unsuitable for rapid processing due to large size. We tested microwave-based acceleration.

Methods

As a proof-of-principle study, 9-gauge VAB specimens were taken from eight mastectomy specimens. Forty-two biopsy specimens were processed. Quality of H&E was evaluated in 84 slides, and estrogen receptor (ER), progesterone receptor (PR), E-cadherin, and human epidermal growth factor receptor 2 (HER2) stains were evaluated in six slides. Preoperative biopsy specimens were used as a control.

Results

Diagnostic quality of H&E slides was good in 87%, reasonable in 12%, and low in 1%. Quality of E-cadherin was good in 75% and reasonable in 25%. Quality of ER was good in 83% and reasonable in 17%. PR and both HER2 immunohistochemistry and fluorescence in situ hybridization were good in all slides. Quality of experimental slides was similar to control slides.

Conclusions

Nine-gauge VAB specimens can be processed within 4 hours. Slides are suitable for all routine pathologic stains. This enables a same-day diagnosis.

Breast Cancer Biomarkers: Challenges in Routine Estrogen Receptor, Progesterone Receptor, and HER2/neu Evaluation

Context.—

Evaluation of estrogen receptor (ER), progesterone receptor (PR), and HER2/neu (HER2) biomarkers is standard of care for all cases of newly diagnosed invasive, recurrent, and metastatic breast cancer. Repeat analysis is also performed in select cases per College of American Pathologists/American Society of Clinical Oncology guidelines and other clinical indications. However, in specific scenarios, preanalytic and analytic variables may pose distinct challenges to testing.

Objective.—

To provide a review of select challenges in the testing of commonly performed breast cancer biomarkers ER, PR, and HER2 and outline best practices for overcoming these challenges.

Data Sources.—

Review of College of American Pathologists/American Society of Clinical Oncology recommendations, current literature, and personal experience of the author.

Conclusions.—

Attention must be given to specimen handling to ensure accurate ER, PR, and HER2 biomarker assessment and appropriate management of breast cancer patients.

Preanalytics and Precision Pathology: Pathology Practices to Ensure Molecular Integrity of Cancer Patient Biospecimens for Precision Medicine

Biospecimens acquired during routine medical practice are the primary sources of molecular information about patients and their diseases that underlies precision medicine and translational research. In cancer care, molecular analysis of biospecimens is especially common because it often determines treatment choices and may be used to monitor therapy in real time. However, patient specimens are collected, handled, and processed according to routine clinical procedures during which they are subjected to factors that may alter their molecular quality and composition. Such artefactual alteration may skew data from molecular analyses, render analysis data uninterpretable, or even preclude analysis altogether if the integrity of a specimen is severely compromised. As a result, patient care and safety may be affected, and medical research dependent on patient samples may be compromised. Despite these issues, there is currently no requirement to control or record preanalytical variables in clinical practice with the single exception of breast cancer tissue handled according to the guideline jointly developed by the American Society of Clinical Oncology and College of American Pathologists (CAP) and enforced through the CAP Laboratory Accreditation Program. Recognizing the importance of molecular data derived from patient specimens, the CAP Personalized Healthcare Committee established the Preanalytics for Precision Medicine Project Team to develop a basic set of evidence-based recommendations for key preanalytics for tissue and blood specimens. If used for biospecimens from patients, these preanalytical recommendations would ensure the fitness of those specimens for molecular analysis and help to assure the quality and reliability of the analysis data.

Factors affecting KRAS mutation detection in colorectal cancer tissue

BACKGROUND

With the recent development of molecular tests for various biomarkers, it has become even more important to prepare adequate tissue samples. However, little is known about how the effect of cold ischemia time or formalin fixation time can affect KRAS mutation detection in colorectal cancer.

METHODS

This study included the results of KRAS mutation tests for colorectal cancer in 401 specimens. We investigated clinicopathologic factors that may affect DNA quality of formalin-fixed, paraffin-embedded (FFPE) tissue including specimen type, cold ischemia time, and formalin fixation time and assessed the detection rate of the KRAS mutation in samples with varying DNA quality.

RESULTS

Sample DNA quality for KRAS mutation test was better in biopsy specimens, which showed markedly shorter cold ischemia time and shorter formalin fixation time compared to resection specimens. A cold ischemia time of one hour or less was associated with better sample DNA quality. But the formalin fixation time was not a significant factor when it fell within the range performed in routine pathology diagnosis. When prolonged formalin fixation was tested, we confirmed that the specimen DNA quality gradually got worse from one month to three months.

CONCLUSIONS

The biopsy specimens showed better sample DNA quality for KRAS mutation test compared to resection specimens. In a routine diagnostic pathology setting, the cold ischemia time was an important factor affecting DNA quality and the formalin fixation had a wide time range for optimal DNA quality.

Assessment of HER2 status in breast cancer biopsies is not affected by accelerated tissue processing

AIMS

To establish whether core needle biopsy (CNB) specimens processed with an accelerated processing method with short fixation time can be used to determine accurately the human epidermal growth factor receptor 2 (HER2) status of breast cancer.

METHODS AND RESULTS

A consecutive case-series from two high-volume breast clinics was created. We compared routine HER2 immunohistochemistry (IHC) assessment between accelerated processing CNB specimens and routinely processed postoperative excision specimens. Additional amplification-based testing was performed in cases with equivocal results. The formalin fixation time was less than 2 h and between 6 and 72 h, respectively. Fluorescence in-situ hybridisation and multiplex ligation-dependent probe amplification were used for amplification testing. One hundred and forty-four cases were included, 15 of which were HER2-positive on the routinely processed excision specimens. On the CNB specimens, 44 were equivocal on IHC and required an amplification-based test. Correlation between the CNB specimens and the corresponding excision specimens was high for final HER2 status, with an accuracy of 97% and a kappa of 0.85.

CONCLUSIONS

HER2 status can be determined reliably on CNB specimens with accelerated processing time using standard clinical testing methods. Using this accelerated technology the minimum 6 h of formalin fixation, which current guidelines consider necessary, can be decreased safely. This allows for a complete and expedited histology-based diagnosis of breast lesions in the setting of a one-stop-shop, same-day breast clinic.

A rapid triage protocol to optimize cold ischemic time for breast resection specimens

Prolonged time from specimen excision to adequate formalin exposure, or cold ischemic time (CIT), negatively impacts estrogen receptor (ER), progesterone receptor (PR) and HER-2 biomarker studies routinely performed on breast specimens. Current guidelines recommend CIT of ≤1 h. Since formalin penetrates resections slowly, optimal fixation requires incision. We evaluated the efficacy of a rapid triage protocol developed to optimize CIT. We identified 2821 specimens: 650 (23.0%) excisional biopsies (EB), 1051 (37.3%) lumpectomies, and 1120 (39.7%) mastectomies. CIT was available for 2362 (83.7%), with 1845 (78.1%) ≤1 h and 2323 (98.3%) ≤4 h. IHC was performed in 533/2821 (18.9%) and was associated with lumpectomy and mastectomy procedures when compared to EB. However, IHC was also performed on 11.1% (72/650) of EB specimens despite EB being significantly less likely to have CIT recorded (468/650; 72% for EB vs. 1894/2171; 87.2% for lumpectomies/mastectomies). Our study highlights the need for rapid triage of breast resections with known or suspected malignant diagnoses and outlines our procedure for optimizing CIT. Additionally, we advocate treating ALL breast resections as having the potential of being malignant and requiring biomarker studies for which optimal CIT is of great importance.

Effect of fixation time on breast biomarker expression: a controlled study using cell line-derived xenografted (CDX) tumours

AIMS

Altering the length of time specimens are placed in fixative without compromising analytical testing accuracy is a continuous challenge in the anatomical pathology lab. The aim of this study was to determine under controlled conditions the effects of variable fixation time on breast biomarker expression in human breast cancer cell line-derived xenografted (CDX) tumours.

METHODS

CDX tumours using strong oestrogen receptor (ER)-positive, Her2-negative (MCF7) and weak ER-positive, Her2 equivocal (T47D) breast cancer cell lines were fixed for various times ranging from 1 to 336 hours in 10% neutral buffered formalin. CDX tumours were processed according to routine biomarker testing protocols and stained for ER and Her2 immunohistochemistry (IHC) and processed for HER2 fluorescence in situ hybridisation (FISH). The tumours were evaluated using Allred scoring for ER and current ASCO/CAP guidelines for Her2, and by objective cell counting methodology.

RESULTS

No differences were found in expression of ER in either MCF7 or T47D CDX tumours under variable fixation. T47D tumours displayed equivocal Her2 staining when fixed for 24 hours, but fixation for ≤8 hours resulted in consistently negative staining while tumours fixed for >72 hours demonstrated consistent equivocal staining (p<0.01). Cell counting assays revealed only a significant increase in sensitivity in tumours fixed for >72 hours (p<0.01). As expected, FISH results were unaffected by variable fixation.

CONCLUSIONS

Neither shortened nor prolonged fixation affects ER expression, consistent with previous findings. In equivocal Her2-expressing tumours, however, increasing fixation increased the sensitivity of Her2 IHC reporting while not affecting FISH.

Molecular pathology in real time

With the development of sophisticated individualized therapeutic approaches, the role of pathology in classification of tumors is enormously increasing. The solely morphological characterization of neoplastic process is no more sufficient for qualified decision on optimal therapeutic approach. Thus, morphologic diagnosis must be supplemented by molecular analysis of the lesion with emphasis on the detection of status of certain markers used as predictive factors for targeted therapy. Both intrinsic and acquired types of intratumor heterogeneity have an impact at various moments of cancer diagnostics and therapy. The primary heterogeneity of neoplastic tissue represents a significant problem in patients, where only limited biopsy samples from the primary tumor are available for diagnosis, such as core needle biopsy specimens in breast cancer, transthoracic or endobronchial biopsies in lung cancer, or endoscopic biopsies in gastric cancer. Detection of predictive markers may be influenced by this heterogeneity, and the marker detection may be falsely negative or (less probably) falsely positive. In addition, as these markers are often detected in the tissue samples from primary tumor, the differences between molecular features of the primary lesion and its metastases may be responsible for failure of systemic therapy in patients with discordant phenotype between primary and metastatic disease. The fact of tumor heterogeneity must be taken into consideration already in establishing pathological diagnosis. One has to be aware that limited biopsy specimen must not always be fully representative of the entire tumor volume. To overcome these limitations, there does not exist one single simple solution. Examination of more tissue (preference of surgical resection specimens over biopsies, whenever possible), use of ultra-sensitive methods able to identify the minute subclones as a source of possible resistance to treatment, and detection of secondary molecular events from the circulating tumor cells or circulating cell-free DNA are potential solutions how to handle this issue.

Active monitoring of formaldehyde diffusion into histological tissues with digital acoustic interferometry

The preservation of certain labile cancer biomarkers with formaldehyde-based fixatives can be considerably affected by preanalytical factors such as quality of fixation. Currently, there are no technologies capable of quantifying a fixative's concentration or the formation of cross-links in tissue specimens. This work examined the ability to detect formalin diffusion into a histological specimen in real time. As formaldehyde passively diffused into tissue, an ultrasound time-of-flight (TOF) shift of several nanoseconds was generated due to the distinct sound velocities of formalin and exchangeable fluid within the tissue. This signal was resolved with a developed digital acoustic interferometry algorithm, which compared the phase differential between signals and computed the absolute TOF with subnanosecond precision. The TOF was measured repeatedly across the tissue sample for several hours until diffusive equilibrium was realized. The change in TOF from 6-mm thick ex vivo human tonsil fit a single-exponential decay ([Formula: see text]) with rate constants that varied drastically spatially between 2 and 10 h ([Formula: see text]) due to substantial heterogeneity. This technology may prove essential to personalized cancer diagnostics by documenting and tracking biospecimen preanalytical fixation, guaranteeing their suitability for diagnostic assays, and speeding the workflow in clinical histopathology laboratories.

Immunohistochemical Markers of Soft Tissue Tumors: Pathologic Diagnosis, Genetic Contributions, and Therapeutic Options

After ~30 years of widespread usage, immunohistochemistry (IHC) has become a standard method of diagnosis for surgical pathology. Because of the plethora of diagnoses and often subtle nature of diagnostic criteria, IHC finds particular utility in soft tissue tumors. The use of progressively small amounts of tissue for diagnosis highlights the importance of this method. The sensitivity and crispness of IHC stains have progressively improved with the advent of new techniques. Traditionally, IHC detects cell-typic markers that characterize cell phenotypes, such as chromogranin for neuroectodermal tissue, myogenin for skeletal muscle, and cytokeratin for epithelium. However, the advent of genetic discoveries have led to IHC testing for detection of fusion gene products or overexpressed oncogenes associated with deletions and mutations. Proliferation-based markers such as Ki-67 can also be used for prognosis and grading, but more standardization is needed. Development of monoclonal antibody-based pharmaceuticals, such as imatinib or crizotinib, holds the promise of tailored anticancer therapy. IHC thus has assumed importance not only for diagnosis but also for guidance of personalized medicine.

Short formalin fixation and rapid microwave processing do not affect HER2 testing

Correct and consistent results in estrogen and progesterone receptors, HER2 and Ki67 proliferation rate testing are a basic prerequisite for selecting therapy and individualizing prognosis in patients with breast carcinoma. Preanalytic factors, including time from excision to fixation and time and type of fixation, are critical to obtain reproducible and reliable results in these immunohistochemical assays and their relevance has long been stressed. The ASCO-CAP guidelines on HER2 testing indicated that histologic material including both biopsies and surgical specimens must be fixed for at least 6 h in order to obtain reliable results; however, there is a very limited scientific support regarding the setting at 6 h the minimum fixation time. We demonstrate that with a short fixation time (30') and rapid processing with MW technology (69'), it is possible to achieve an adequate and reproducible assessment of HER2 status. We obtained similar results in HER2 evaluation in breast carcinoma biopsies treated with this short protocol and in the corresponding surgical specimens processed routinely with a 24 h formalin fixation time-i.e., within the guidelines interval time.

Bioinformatic analysis of cis-regulatory interactions between progesterone and estrogen receptors in breast cancer

Chromatin factors interact with each other in a cell and sequence-specific manner in order to regulate transcription and a wealth of publically available datasets exists describing the genomic locations of these interactions. Our recently published BiSA (Binding Sites Analyser) database contains transcription factor binding locations and epigenetic modifications collected from published studies and provides tools to analyse stored and imported data. Using BiSA we investigated the overlapping cis-regulatory role of estrogen receptor alpha (ERα) and progesterone receptor (PR) in the T-47D breast cancer cell line. We found that ERα binding sites overlap with a subset of PR binding sites. To investigate further, we re-analysed raw data to remove any biases introduced by the use of distinct tools in the original publications. We identified 22,152 PR and 18,560 ERα binding sites (<5% false discovery rate) with 4,358 overlapping regions among the two datasets. BiSA statistical analysis revealed a non-significant overall overlap correlation between the two factors, suggesting that ERα and PR are not partner factors and do not require each other for binding to occur. However, Monte Carlo simulation by Binary Interval Search (BITS), Relevant Distance, Absolute Distance, Jaccard and Projection tests by Genometricorr revealed a statistically significant spatial correlation of binding regions on chromosome between the two factors. Motif analysis revealed that the shared binding regions were enriched with binding motifs for ERα, PR and a number of other transcription and pioneer factors. Some of these factors are known to co-locate with ERα and PR binding. Therefore spatially close proximity of ERα binding sites with PR binding sites suggests that ERα and PR, in general function independently at the molecular level, but that their activities converge on a specific subset of transcriptional targets.