HER2 testing for breast carcinoma: recommendations for rapid diagnostic pathways in clinical practice

UK recommendations for HER2 assessment in breast cancer: an update

The last UK breast cancer (BC) human epidermal growth factor receptor 2 (HER2) testing guideline recommendations were published in 2015. Since then, new data and therapeutic strategies have emerged. The American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) published a focused update in 2018 that reclassified in situ hybridisation (ISH) Group 2 (immunohistochemistry (IHC) score 2+and HER2/chromosome enumeration probe 17 (CEP17) ratio ≥2.0 and HER2 copy number <4.0 signals/cell), as well as addressed other concerns raised by previous guidelines. The present article further refines UK guidelines, with specific attention to definitions of HER2 status focusing on eight key areas: (1) HER2 equivocal (IHC 2+) and assignment of the ASCO/CAP ISH group 2 tumours; (2) the definition of the group of BCs with low IHC scores for HER2 with emphasis on the distinction between IHC score 1+ (HER2-Low) from HER2 IHC score 0 (HER2 negative); (3) reporting cases showing HER2 heterogeneity; (4) HER2 testing in specific settings, including on cytological material; (5) repeat HER2 testing, (6) HER2 testing turnaround time targets; (7) the potential role of next generation sequencing and other diagnostic molecular assays for routine testing of HER2 status in BC and (8) use of image analysis to score HER2 IHC. The two tiered system of HER2 assessment remains unchanged, with first line IHC and then ISH limited to IHC equivocal cases (IHC score 2+) but emerging data on the relationship between IHC scores and levels of response to anti-HER2 therapy are considered. Here, we present the latest UK recommendations for HER2 status evaluation in BC, and where relevant, the differences from other published guidelines.

The important role of the histopathologist in clinical trials: challenges and approaches to tackle them

High-quality histopathology is essential for the success of clinical trials. Histopathologists have a detailed understanding of tumour biology and mechanisms of disease, as well as practical knowledge of optimal tissue handling and logistical service requirements for study delivery, such as biomarker evaluation, tissue acquisition and turnaround times. As such, histopathologist input is essential throughout every stage of research and clinical trials, from concept development and study design to trial delivery, analysis and dissemination of results. Patient recruitment to trials takes place among all healthcare settings, meaning that histopathologists make an invaluable contribution to clinical trials as part of their routine day-to-day work that often goes unrecognised. More complex evaluation of surgical specimens in the neoadjuvant setting and ever-expanding minimum data sets add to the workload of every histopathologist, not just academic pathologists in tertiary centres. This is occurring against a backdrop of increasing workload pressures and a worldwide shortage of histopathologists and biomedical scientists. Providing essential histopathology support for trials at grassroots level requires funding for adequate resources including histopathologist time, education and training, biomedical scientist and administrative support and greater recognition of the contribution made by histopathology. This paper will discuss the many ways in which histopathologists are involved in clinical trials and the challenges faced in meeting the additional demands posed by trial participation and potential ways to address this, with a special emphasis on the UK model and the Cellular-Molecular Pathology Initiative (CM-Path).

Data mining of digitized health records in a resource-constrained setting reveals that timely immunophenotyping is associated with improved breast cancer outcomes

BACKGROUND

Organizations that issue guidance on breast cancer recommend the use of immunohistochemistry (IHC) for providing appropriate and precise care. However, little focus has been directed to the identification of maximum allowable turnaround times for IHC, which is necessary given the diversity of hospital settings in the world. Much less effort has been committed to the development of digital tools that allow hospital administrators to monitor service utilization histories of their patients.

METHODS

In this retrospective cohort study, we reviewed electronic and paper medical records of all suspected breast cancer patients treated at one secondary-care hospital of the Mexican Institute of Social Security (IMSS), located in western Mexico. We then followed three years of medical history of those patients with IHC testing.

RESULTS

In 2014, there were 402 breast cancer patients, of which 30 (7.4% of total) were tested for some IHC biomarker (ER, PR, HER2). The subtyping allowed doctors to adjust (56.7%) or confirm (43.3%) the initial therapeutic regimen. The average turnaround time was 56 days. Opportune IHC testing was found to be beneficial when it was available before or during the first rounds of chemotherapy.

CONCLUSIONS

The use of data mining tools applied to health record data revealed that there is an association between timely immunohistochemistry and improved outcomes in breast cancer patients. Based on this finding, inclusion of turnaround time in clinical guidelines is recommended. As much of the health data in the country becomes digitized, our visualization tools allow a digital dashboard of the hospital service utilization histories.

Robust and accurate digital measurement for HER2 amplification in HER2 equivocal breast cancer diagnosis

Currently, there are no recommended alternative assays for HER2 cases deemed equivocal by immunohistochemistry and fluorescent in situ hybridization. Digital PCR (ddPCR), a highly accurate method to determine DNA copy number, could be a robust alternative for clinical HER2 diagnostics. HER2 and CEP17 copy numbers were quantified using two ddPCR platforms (QX200 and RainDrop) in 102 samples of invasive breast cancers. Compared to routine assays, ddPCR gave a sensitivity and specificity of 82.8% and 97.3% respectively, with a kappa value of 0.833 (p < 0.001). Moreover, the method proved to be robust as the results from two platforms was highly correlated (R² = 0.91; Concordance rate = 97%; κ = 0.923, P < 0.001). Its performance was further tested on 114 HER2 equivocal cases in an independent validation cohort. 75% (21/28) of cases with HER2 amplification and 95% (82/86) of HER2 non-amplified case were classified as positive and negative by ddPCR respectively (κ = 0.709, P < 0.001). Notably, in the HER2 amplified cases, a lower percentage of HER2 positive cells could be related to the discordant results. Altogether, ddPCR is a robust alternative for clinical HER2 diagnostics. However, intratumoral heterogeneity of HER2 status still pose a challenge for HER2 analysis by ddPCR.

Comparative Analysis of Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer According to 2007 and 2013 American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations

Purpose To study the effect of the 2013 updates to the 2007 American Society of Clinical Oncology/College of American Pathologists recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer on testing patterns and interpretation in a large regional reference laboratory. Patients and Methods Patient cases with HER2 testing scores for breast biomarker evaluation were selected from our laboratory information system during two 12-month periods (2012 and 2014). The number of tests performed, type of specimens, proportion of HER2-positive and equivocal patient cases, and number of repeat tests on subsequent excisional specimens were examined and compared. Results Although the number of samples tested increased between 2012 and 2014 (2,201 v 2,558 patient cases; 2,278 v 2,659 tumors), HER2 positivity remained constant (15.7% v 15.5%, respectively). The number of repeat tests performed within 6 months more than doubled (122 [5.5%) of 2,201 v 302 [11.8%] of 2,558; P < .001), and the proportion of immunohistochemistry (IHC) 2+ tumors was significantly lower in 2014 than in 2012 (20.3% v 25.3%; P < .001). However, the proportion of patient cases with unresolved HER2 statuses (equivocal by IHC and in situ hybridization) was significantly higher in 2014 (four of 2,278 v 90 of 2,660; P < .001). Conclusion Our findings indicate that the 2013 updates to the American Society of Clinical Oncology/College of American Pathologists recommendations for HER2 testing in breast cancer did not affect the overall HER2-positivity rate or the proportion of patients eligible for HER2-targeted therapy. The proportion of tests and repeat tests performed increased, as did the number of patient cases categorized as ISH equivocal. The benefit of targeted therapy in the equivocal group is not proven, so targeted therapy should not be considered for patients in this category which should be redefined in future iterations of the recommendations.

Reflex Repeat HER2 Testing of Grade 3 Breast Carcinoma at Excision Using Immunohistochemistry and In Situ Analysis: Frequency of HER2 Discordance and Utility of Core Needle Biopsy Parameters to Refine Case Selection

OBJECTIVES

The updated American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines (2013) for human epidermal growth factor receptor 2 (HER2) testing in breast cancer recommend repeat testing at excision of HER2-negative grade 3 breast tumors. This study aimed to identify the rate of HER2 discordance in this cohort of cases.

METHODS

All HER2-negative grade 3 tumors diagnosed at a single institution over a 15-month period had reflex repeat HER2 testing at excision : HER2 testing was performed in accordance with ASCO/CAP guidelines using immunohistochemistry (IHC) and dual in situ hybridization (ISH).

RESULTS

One hundred cases were identified over the study period. HER2 was amplified at excision in three cases. The discordant tumors showed equivocal IHC at excision with low-level amplification on dual ISH. All discordant cases showed equivocal IHC on core needle biopsy (CNB) specimens and/or tumor upgrade at excision.

CONCLUSIONS

Our series demonstrated a high concordance rate (97%) for HER2 at excision in grade 3 breast tumors with a negative core biopsy result. These findings suggest that reflex repeat HER2 testing of all these cases, which has significant cost and workload implications, may not be justified. Features that may indicate HER2 heterogeneity, such as equivocal IHC on CNB specimens or tumor upgrade at excision, may help refine selection of cases for repeat testing.

Expression of CPEB4 in invasive ductal breast carcinoma and its prognostic significance

Aims

Cytoplasmic polyadenylation element binding proteins (CPEBs) are RNA-binding proteins that regulate translation by inducing cytoplasmic polyadenylation. CPEB4 has been reported in association with tumor growth, vascularization, and invasion in several cancers. To date, the expression of CPEB4 with clinical prognosis of breast cancer was never reported before. We aim to investigate the expression of CPEB4 and its prognostic significance in invasive ductal breast carcinoma.

Methods

Immunohistochemical staining of CPEB4 and estrogen receptor, progesterone receptor, and human epidermal growth factor receptor was performed in 107 invasive ductal carcinoma (IDC) samples, and prognostic significance was evaluated.

Results

High expression of CPEB4 was observed in 48.6% of IDC samples. Elevated CPEB4 expression was possibly related to increased histological grading (P=0.037) and N stage (P<0.001). Patients with high expression of CPEB4 showed shorter overall survival (P=0.001). High CPEB4 expression was an independent prognostic factor for overall survival (P=0.022, hazard ratio =4.344, 95% confidence interval =1.235–15.283).

Conclusion

High CPEB4 expression is associated with increased histological grading and N stage, and it can serve as an independent prognostic factor in IDC.

Human epidermal growth factor receptor 2 testing in invasive breast cancer: should histological grade, type and oestrogen receptor status influence the decision to repeat testing?

AIMS

The recent American Society of Clinical Oncology/College of American Pathologists guidelines for human epidermal growth factor receptor 2 (HER2) testing in breast cancer recommend repeat testing based on tumour grade, tumour type, and hormone receptor status. The aim of this study was to test the value of these criteria.

METHODS AND RESULTS

HER2 status was concordant in the core biopsies and excision specimens in 392 of 400 invasive carcinomas. The major reasons for discordance were amplification around the cut-off for positivity and tumour heterogeneity. Of 116 grade 3 carcinomas that were HER2-negative in the core biopsy, four were HER2-positive in the excision specimen. Three of these four either showed borderline negative amplification in the core biopsy or were heterogeneous. None of the 55 grade 1 carcinomas were HER2-positive. Review of repeat testing of HER2 in routine practice suggested that it may also be of value for multifocal tumours and if recommended by the person assessing the in-situ hybridization.

CONCLUSIONS

Mandatory repeat HER2 testing of grade 3 HER2-negative carcinomas is not appropriate. This is particularly true if repeat testing is performed after borderline negative amplification in the core biopsy or in HER2-negative heterogeneous carcinomas.

Macroscopic handling and reporting of breast cancer specimens pre- and post-neoadjuvant chemotherapy treatment: review of pathological issues and suggested approaches

Neoadjuvant chemotherapy (NACT) is used increasingly in the treatment of invasive breast cancer and presents challenges for the pathologist in the handling and interpretation of tissues. Potential issues include pathological identification and localization of the residual tumour site; how best to assess pathological response (given the diversity of scoring systems described); the timing and assessment of axillary node biopsy; and the value of retesting any residual tumour for dissonance between core biopsy and post-treatment residual cancer cells for biomarker expression such as oestrogen and progesterone receptors and human epidermal growth factor receptor 2 (HER2). The role of the pathologist is critical in modern NACT approaches to breast cancer and is likely to remain challenging as novel agents and newer biomarkers become available. In this manuscript we review these issues and describe some practical approaches to handling and reporting these samples in the routine histopathology laboratory.