Comparison of the prognostic effect of pyrotinib plus trastuzumab and chemotherapy different lines therapy in HER2-positive advanced breast cancer

This study aimed to compare the efficacy of pyrotinib, trastuzumab combined with chemotherapy with different lines therapy in human epidermal growth factor receptor 2- (HER2-) positive advanced breast cancer (ABC) and analyze the factors affecting the prognosis. A total of 84 patients with median age of 49 year-old. The mPFS of patients receiving first-line pyrotinib plus trastuzumab and chemotherapy was the longest (11 months) compared with second- and third line patients (p = 0.106). The objective response rate (ORR) and disease control rate (DCR) of the total population were 33.3% and 82.1% respectively. Subgroup analysis suggested that using pyrotinib plus trastuzumab and Albumin-bound paclitaxel was not inferior to combine with Vinorelbine in regards of PFS. Histological grade (OR: 0.233[0.069 ∼ 0.781], p = 0.018) and tumor location (OR: 0.286[0.087 ∼ 0.942], p = 0.040) were independent factors influencing the ORR. Multivariate cox analysis showed that Ki-67 was independently associated with increased risk of progression (HR: 1.843[1.044-3.254], p = 0.035). The most common adverse events were diarrhea (17.9%) and neutropenia (11.9%). In the first-, second- and third-line treatment, pyrotinib plus trastuzumab and chemotherapy is effective and safe. Pyrotinib and trastuzumab combined with Albumin-bound paclitaxel may be a potential ideal treatment plan for HER2-positive advanced breast cancer.

HER2 fluorescence in situ hybridization groups 2-4 breast cancers classified as positive after targeted recounts following equivocal (2+) immunohistochemistry

OBJECTIVES

To investigate the correlation between the extent of (percentage of tumor cells) immunohistochemistry (IHC) staining and final human epidermal growth factor receptor 2 (HER2)-positive result in fluorescence in situ hybridization (FISH) groups 2 to 4 with equivocal (2+) IHC requiring second, blinded FISH evaluation.

METHODS

Breast cancer cases submitted for HER2 FISH testing with group 2 to 4 results were included.

RESULTS

Of the 2548 cases with HER2 FISH groups 2 to 4 that had HER2 IHC performed, 1104 (43.3%) (76/182 [41.8%] of group 2, 94/161 [58.4%] of group 3, 934/2205 [42.4%] of group 4) had equivocal (2+) IHC. After second blinded, IHC-guided recounts, 217 of 1104 (19.7%) (17/76 [22.4%], 75/94 [79.8%], 125/934 [13.4%] of FISH groups 2, 3, 4 with IHC 2+, respectively) had final HER2-positive status. Only 13 of 217 (6%) of the cases with HER2-positive status had more than 50% circumferential staining of the tumor targeted for rescoring.

CONCLUSIONS

In over 90% of HER2 FISH group 2 to 4 breast cancers with equivocal (2+) IHC followed by targeted, blinded second FISH evaluation and final HER2-positive result, the amplified population of tumor cells was limited (<50%). Current guidelines recommend cancers having 10% to 50% of the subpopulation with amplified cells classified as having genetic heterogeneity (GH), which have a poor response to targeted therapies. Identifying these tumors as having GH and/or repeat testing may be recommended.

Clinicopathologic Characteristics and Follow-Up Outcomes of Invasive Breast Carcinoma With Different Positive HER2 Fluorescence In Situ Hybridization Patterns: Experience From a Single Academic Institution

Human epidermal growth factor receptor 2 (HER2)-positive breast carcinoma (BC) encompasses a spectrum of molecular subtypes, characterized by varying HER2/CEP17 ratios and HER2 copy numbers, influencing responses to anti-HER2 therapy. This study stratified HER2 fluorescence in situ hybridization (FISH)-positive patients into 3 distinct groups-group 1 with high copy number (G1-HC: ratio ≥2, copy number ≥6), group 1 with low copy number (G1-LC: ratio ≥2, copy number ≥4 and <6), and group 3 (G3: ratio <2.0, copy number ≥6.0)-and evaluated their clinicopathologic features, response to anti-HER2 therapy, and outcomes. In a cohort of 2702 continuous primary BCs, G1-HC BCs accounted for 304 cases (11.3%), G1-LC for 37 cases (1.4%), and G3 for 75 cases (2.8%). G1-HC BCs were associated with younger age, higher tumor grade, and estrogen receptor negativity compared with G1-LC BCs. Furthermore, G1-HC BCs exhibited increased progesterone receptor negativity and HER2 immunohistochemistry 3+ compared with G1-LC and G3 BCs. Analysis of the subgroup of HER2 immunohistochemistry 2+-only cases (n = 166) showed similar results. Notably, G1-HC patients exhibited significantly enhanced responses to anti-HER2 neoadjuvant chemotherapy compared with G1-LC and G3 patients. Conversely, G1-LC patients displayed a lower likelihood of disease-free status compared with G1-HC and G3 patients, albeit with no significant differences in overall survival, distant metastasis, or local recurrence among the groups. These findings offer valuable clinicopathologic insights into different HER2 FISH positive subgroups, potentially informing future criteria for interpreting HER2 FISH results.

Clinicopathologic Features and Digital Imaging Analysis of HER2 Protein in Breast Carcinomas With Different HER2 Fluorescence in Situ Hybridization Patterns

BACKGROUND

HER2-targeted therapies have significantly improved outcomes for patients with HER2-positive breast cancer (BC), which represents 15% to 20% of all BC cases. HER2 status is assessed via immunohistochemistry (IHC) and/or in situ hybridization (ISH), dividing BCs into five groups (G1-G5).

PATIENTS AND METHODS

In a study of 2,702 primary BC cases, comprising 12.7% G1, 0.2% G2, 2.8% G3, 8.5% G4, and 75.9% G5, we analyzed clinicopathologic features and HER2 protein expression digitally for each ISH group.

RESULTS

Notably, G5 cases had a higher proportion of lobular carcinoma (13.9%) compared to other groups. G3 cases showed the highest percentage of grade 3 tumors (56.9%), while G5 cases had the lowest (21.4%). Additionally, G5 cases had the highest rate of estrogen receptor (ER) positivity (84.6%), while G1-HC (high copy number) cases had the lowest (70.4%). Most G1-HC cases were HER2 IHC 3+ (76.1%), while most G5 cases were IHC 0/1+ (75.7%). IHC 2+ was most common in G1-LC (low copy number) and G3 cases (83.8% and 90.7%, respectively), with G4 cases predominantly IHC 2+ (56.3%) and IHC 1+ (30.1%). Discordant HER2 IHC and ISH results were observed in 12 cases (0.4%), including 7 G1-HC (2.3%), 4 G1-LC (10.8%), and 1 G5 case (0.1%). Digital quantification of HER2 IHC levels in all groups except G5 revealed that G1-HC tumors had the highest HER2 protein expression, followed by G3, with G4 showing the lowest.

CONCLUSION

These findings offer valuable insights into the clinicopathologic characteristics and future management for different HER2 ISH groups.

Human epidermal growth factor receptor 2 (HER2) status in breast cancer: practice points and challenges

Human epidermal growth factor receptor 2 (HER2)-enriched breast cancer benefits significantly from anti-HER2 targeted therapies. This highlights the critical need for precise HER2 immunohistochemistry (IHC) interpretation serving as a triage tool for selecting patients for anti-HER2 regimens. Recently, the emerging eligibility of patients with HER2-low breast cancers for a novel HER2-targeted antibody-drug conjugate (T-DXd) adds challenges to HER2 IHC scoring interpretation, notably in the 0-1+ range, which shows high interobserver and interlaboratory staining platform variability. In this review, we navigate evolving challenges and suggest practical recommendations for HER2 IHC interpretation.

Breast Cancer With HER2 Immunohistochemical Score 2 and Average HER2 Signals/Cell 6 or More and HER2/CEP17 Ratio Less Than 2 ('ISH Group 3'): A Multi-Institutional Cohort Analysis Emphasizing Outcome and Molecular Subtype

Breast cancer (BC) with average human epidermal growth factor receptor 2 (HER2) signals/cell ≥6 and HER2/chromosome enumeration probe 17 (CEP17) ratio <2 (in situ hybridization [ISH] group 3) is very rare, accounting for 0.4% to 3.0% of cases sent for the dual-probe ISH assay. Although such patients are currently eligible for treatment with HER2-targeted therapy, their characteristics and outcomes remain poorly understood. Sixty-two BCs with equivocal HER2 immunohistochemical score (2+) and reflex ISH group 3 results were identified across 4 institutions. Available clinicopathologic characteristics, MammaPrint and BluePrint molecular results, and follow-up information were retrospectively analyzed. Most BCs with HER2 equivocal immunohistochemical and ISH group 3 results were histologic grade 2 or 3 (100%), estrogen receptor (ER) positive (90.3%), with an average HER2 signals/cell of 7.3. Molecular profiles revealed that 80% (16/20) of tumors were luminal subtypes, and HER2 molecular subtype was identified in 10% of tumors (2/20). Twelve (19.4%) out of 62 patients developed local recurrence and/or distant metastasis with a median follow-up of 50 months. One (10%) of 10 patients achieved pathologic complete response after neoadjuvant chemotherapy. Forty-nine (79%) out of 62 patients completed anti-HER2 agents, and exploratory analysis showed no statistically significant difference in disease outcomes between patients who completed anti-HER2 treatment and those who did not. Univariate analysis revealed advanced clinical stage, and ER/progesterone receptor negativity was associated with unfavorable disease outcomes, and exploratory multivariate analysis demonstrated that clinical stage was the most significant factor associated with disease outcomes in the studied population. These findings increase our understanding of this rare, but clinically important HER2 category. Large-scale prospective randomized studies are needed to further evaluate the role of perioperative HER2-targeted therapy in this patient population.

Vision Transformers for Breast Cancer Human Epidermal Growth Factor Receptor 2 Expression Staging without Immunohistochemical Staining

Accurate staging of human epidermal growth factor receptor 2 (HER2) expression is vital for evaluating breast cancer treatment efficacy. However, it typically involves costly and complex immunohistochemical staining, along with hematoxylin and eosin staining. This work presents customized vision transformers for staging HER2 expression in breast cancer using only hematoxylin and eosin-stained images. The proposed algorithm comprised three modules: a localization module for weakly localizing critical image features using spatial transformers, an attention module for global learning via vision transformers, and a loss module to determine proximity to a HER2 expression level based on input images by calculating ordinal loss. Results, reported with 95% CIs, reveal the proposed approach's success in HER2 expression staging: area under the receiver operating characteristic curve, 0.9202 ± 0.01; precision, 0.922 ± 0.01; sensitivity, 0.876 ± 0.01; and specificity, 0.959 ± 0.02 over fivefold cross-validation. Comparatively, this approach significantly outperformed conventional vision transformer models and state-of-the-art convolutional neural network models (P < 0.001). Furthermore, it surpassed existing methods when evaluated on an independent test data set. This work holds great importance, aiding HER2 expression staging in breast cancer treatment while circumventing the costly and time-consuming immunohistochemical staining procedure, thereby addressing diagnostic disparities in low-resource settings and low-income countries.

Invasive Breast Cancer with HER2 ≥4.0 and <6.0: Risk Classification and Molecular Typing by a 21-Gene Expression Assay and MammaPrint Plus BluePrint Testing

PURPOSE

To investigate the HER2 status and clinicopathological features in invasive breast cancer with HER2 ≥4.0 and <6.0, which has always been controversial.

METHODS

Forty breast cancer cases with HER2 ≥4.0 and <6.0 by fluorescence in situ hybridization (FISH) were collected and classified into two groups based on the HRE2/CEP17 ratio (Group A: ≥2.0, n=22; Group B: <2.0, n=18). Clinicopathological characteristics, HER2 status, risk classification, and molecular typing were further analyzed and compared by 21-Gene expression assay and MammaPrint plus BluePrint test.

RESULTS

The majority of cases in both groups were invasive carcinoma (NOS), with histological grade II, HR+, Ki-67 ≥20%, HER2 2+, and a high risk of recurrence, although younger patients and lymph node metastases were more common in Group A. Surprisingly, all HR+ breast cancers in both groups were classified as luminal-type, HR- cases were all basal-type or unknown, and the index of HER2 in all cases was <0.000 using the BluePrint test, which indicated that HER2 status should be negative. Furthermore, the level of HER2 mRNA expression in all cases of both groups was <10.7, which was defined as HER2 negative by the 21-Gene expression assay. In addition, 10 patients of Group A received anti-HER2 neoadjuvant therapy; only one patient with HR- achieved Grade 5 based on the Miller-Payne system, whereas none of the patients achieved pathological complete response (pCR) based on the Residual Cancer Burden system.

CONCLUSION

Group A breast cancer, which has always been unquestionably diagnosed as HER2 amplification, was more likely to be HER2 negative and derived less benefit from anti-HER2 neoadjuvant chemotherapy. Group A breast cancer should be distinguished from classical HER2-positive breast cancers when assessing HER2 FISH, and a larger cohort of Group A patients should be included in further studies.

Comparisons of clinical characteristics, prognosis, epidemiological factors, and genetic susceptibility between HER2-low and HER2-zero breast cancer among Chinese females

BACKGROUND

Traditional human epidermal growth factor receptor 2 (HER2)-negative breast cancer (BC) is recommended to be divided into HER2-low and HER2-zero subtypes due to different prognosis. However, few studies investigated their differences in clinical characteristics and prognosis among Chinese HER2-negative BC and their stratified differences by hormone receptor (HR), while fewer studies investigated their differences in epidemiological factors and genetic susceptibility.

METHODS

A total of 11,911 HER2-negative BC were included to compare the clinical characteristics and prognosis between HER2-zero and HER2-low BC, and 4227 of the 11,911 HER2-negative BC were further compared to 5653 controls to investigate subtype-specific epidemiological factors and single nucleotide polymorphisms(SNPs).

RESULTS

Overall, 64.2% of HER2-negative BC were HER2-low BC, and the stratified proportions of HER2-low BC were 61.9% and 75.2% for HR-positive and HR-negative BC, respectively. Compared to HER2-zero BC, HER2-low BC among HR-positive BC showed younger age at diagnosis, later stage, poorer differentiation, and higher Ki-67, while elder age at diagnosis and lower mortality were observed for HER2-low BC among HR-negative BC (all p values <0.05). Compared to healthy controls, both HER2-low and HER2-zero BC are associated with similar epidemiological factors and SNPs. However, stronger interaction between epidemiological factors and polygenic risk scores were observed for HER2-zero BC than HER2-low BC among either HR-positive [odds ratios: 10.71 (7.55-15.17) and 8.84 (6.19-12.62) for the highest risk group compared to the lowest risk group] or HR-negative BC [7.00 (3.14-15.63) and 5.70 (3.26-9.98)].

CONCLUSIONS

HER2-low BC should deserve more attention than HER2-zero BC, especially in HR-negative BC, due to larger proportion, less clinical heterogeneity, better prognosis, and less susceptibility to risk factors.

A clinicopathological study and survival analysis of 99 breast cancers with HER2/CEP17 ratio ≥ 2.0 and an average HER2 copy number < 4.0 per cell in China

BACKGROUND

Breast cancer patients of American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) Group 2 were all HER2-negative according to the 2018 guideline, not HER2-positive as defined in the 2013 guideline.

METHODS

We aims to elucidate the unique clinicopathological features of ASCO/CAP Group 2 patients by comparing with classic HER2-nonamplified cancers, and reveal the efficacy of the former to anti-HER2 therapy. The clinicopathological features, treatment and prognosis information of 99 patients between 2014 and 2018 were collected. HER2 status was re-defined using the updated recommendations.

RESULTS

Of the 99 ASCO/CAP Group 2 tumors, 25.5% (25/99) tumors were immunohistochemical (IHC) 0/1+ and 74.7% (74/99) tumors were IHC 2+. According to the updated 2018 guideline, all of them were HER2 negative. When compared to ASCO/CAP Group 5, patients of ASCO/CAP Group 2 displayed higher ratio of histological grade 3 (P = .03), high Ki67 proliferation index (P = .03) and pN3 (more than 9 lymph nodes metastasis, P = .02), and lower estrogen receptor (ER) positivity (P = .04). There was no statistical difference in the survival of patients received anti-HER2 therapy and patients not received anti-HER2 therapy.

CONCLUSIONS

Patients of ASCO/CAP Group 2 did not received apparent benefit from anti-HER2 treatment. Although according to the updated guidelines and latest reports, HER2 is negative, but when compared with classic HER2-nonamplified cancers, patients of this group seemed to be more aggressive. We suggest that this group still be regarded as an independent category, in order to accumulate more cases in the future to expand the scope of research.

Comparison of HercepTest™ mAb pharmDx (Dako Omnis, GE001) with Ventana PATHWAY anti-HER-2/neu (4B5) in breast cancer: correlation with HER2 amplification and HER2 low status

Performance of the new CE-IVD-marked HercepTest™ mAb pharmDx (Dako Omnis) assay (HercepTest (mAb)) was compared against the PATHWAY® anti-HER-2/neu (4B5) (PATHWAY 4B5) assay using 119 pre-selected breast cancer samples covering the entire range of HER2 immunohistochemistry (IHC) expression scores (0, 1 + , 2 + , 3 +). The sensitivity and specificity of both assays were assessed based on consensus IHC scores and amplification status, as determined by fluorescence in situ hybridization (FISH) according to 2018 ASCO/CAP testing guidelines. There was a high concordance between results from the HercepTest (mAb) and PATHWAY 4B5 assays for HER2-negative (IHC 0, 1 + , 2 + and FISH negative) and HER2-positive (IHC 3 + , 2 + and FISH positive) breast carcinomas (98.2%). Regarding individual IHC scores, complete agreement was achieved in 69.7% (83/119) of cases, and all but one of the discordant cases were due to higher HER2-status scoring using the HercepTest (mAb). Thus, more tumors were overscored as IHC 2 + by HercepTest (mAb) (27 versus 15) as evidenced by their lower FISH positivity rate (48.1% versus 80%). However, two amplified tumors identified as IHC 2 + by HercepTest (mAb) were missed by PATHWAY 4B5 (IHC 1 +). Four additional cases identified as IHC 2 + by HercepTest (mAb), with FISH ratio < 2 but elevated gene counts (≥ 4 to < 6), were recorded negative by PATHWAY 4B5. The HercepTest (mAb) detects HER2 expression with higher sensitivity in tumors with gene amplification (ISH group 1) and increased gene counts (ISH group 4) as well as in HER2-low tumors (HER2 IHC2 + /FISH negative or IHC 1 +). Future studies will demonstrate whether this translates into improved patient selection especially for new HER2-directed therapies.

Computer-Aided Scoring Of () Gene Amplification Status In Breast Cancer

Background

Identification of HER2 protein overexpression and/or amplification of the HER2 gene are required to qualify breast cancer patients for HER2 targeted therapies. In situ hybridization (ISH) assays that identify HER2 gene amplification function as a stand-alone test for determination of HER2 status and rely on the manual quantification of the number of HER2 genes and copies of chromosome 17 to determine HER2 amplification.

Methods

To assist pathologists, we have developed the uPath HER2 Dual ISH Image Analysis for Breast (uPath HER2 DISH IA) algorithm, as an adjunctive aid in the determination of HER2 gene status in breast cancer specimens. The objective of this study was to compare uPath HER2 DISH image analysis vs manual read scoring of VENTANA HER2 DISH-stained breast carcinoma specimens with ground truth (GT) gene status as the reference. Three reader pathologists reviewed 220, formalin-fixed, paraffin-embedded (FFPE) breast cancer cases by both manual and uPath HER2 DISH IA methods. Scoring results from manual read (MR) and computer-assisted scores (image analysis, IA) were compared against the GT gene status generated by consensus of a panel of pathologists. The differences in agreement rates of HER2 gene status between manual, computer-assisted, and GT gene status were determined.

Results

The positive percent agreement (PPA) and negative percent agreement (NPA) rates for image analysis (IA) vs GT were 97.2% (95% confidence interval [CI]: 95.0, 99.3) and 94.3% (95% CI: 90.8, 97.3) respectively. Comparison of agreement rates showed that the lower bounds of the 95% CIs for the difference of PPA and NPA for IA vs MR were –0.9% and –6.2%, respectively. Further, inter- and intra-reader agreement rates in the IA method were observed with point estimates of at least 96.7%.

Conclusions

Overall, our data show that the uPath HER2 DISH IA is non-inferior to manual scoring and supports its use as an aid for pathologists in routine diagnosis of breast cancer.

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Image analysis algorithm for HER2 amplification using Bright-field ISH in Breast.

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Automated tumor cell selection and quantitation within pathologist defined ROI.

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The image analysis algorithm is non-inferior to manual scoring.

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Integrated solution to support pathologists in determining HER2 gene status.

HER2 copy number quantification in primary tumor and cell-free DNA provides additional prognostic information in HER2 positive early breast cancer

BACKGROUND

The quantitative relationship between HER2 copy number and prognosis in HER2 positive adjuvant setting remain controversial, and few studies have focused on adjuvant setting to illustrate the potential clinical relevance of HER2 in cfDNA. Our study aim to develop a novel method in HER2 quantification and explore the relationship between HER2 copy number in primary tumors or cfDNA and prognosis in HER2 positive early breast cancer.

METHODS

Two hundred and two patients with early breast cancer were prospectively included in a study where primary tumors, matching non-cancer breast tissue, corresponding plasma, and the plasma from 20 healthy volunteers were collected. Cox proportional hazard analysis was employed to determine the prognostic value of HER2 gene copy number in tissue and cfDNA. Tissue based nomograms and time-dependent decision curve analysis were used to evaluate the practicality of HER2 copy number stratification.

RESULTS

HER2 amplification by CNVplex demonstrated a robust concordance with FISH (concordance 89.2%). A three-tiered system of tissue and a two-tiered system of cfDNA classification were shown to be independent prognostic factors. A tissue copy number-based nomogram was fitted and further evaluation revealed a good performance in discrimination (c statistic 0.801) and calibration.

CONCLUSIONS

We first report CNVplex as a viable alternative for HER2 detection. Quantitative evaluation of HER2 presents tremendous potential for use in risk stratification. We also uncover the potential for using HER2 copy number in cfDNA as a biomarker for prognosis in a HER2 positive adjuvant setting.

Histologic analysis according to HER2 gene status in HER2 2 + invasive breast cancer: a study of 280 cases comparing ASCO/CAP 2013 and 2018 guideline recommendations

The American Society of Clinical Oncology and College of American Pathologists guidelines for HER2 testing in breast cancer (BC) have been updated with more stringent criteria regarding immunohistochemistry (IHC) 2 + interpretation. The aim of our study was to determine HER2 status in IHC 2 + cases based on 2013 and 2018 guidelines and to investigate specific histologic characteristics that might predict HER2 status in tumors with equivocal IHC staining. Two hundred eighty BC cases reported as IHC 2 + and 24 cases reported as non-IHC 2 + were reviewed with 12 histologic characteristics. Of the IHC 2 + cases based on 2013 guideline, 21% were reclassified to IHC 1 + when applying the 2018 guidelines. Consequently, it led to an 8% increase of HER2 amplification rate in 2018 IHC 2 + group. Seven characteristics were significantly associated with prediction of HER2 amplification in IHC 2 + BCs, including high tumor-infiltrating lymphocytes (TILs), distinct cellular membrane, no apical snout, large nuclear size, nuclear size variation, high nuclear grade, and tubule formation < 10%. Using these criteria, the presence of four or more characteristics significantly indicates HER2 amplification. Moreover, four characteristics among them, including high TILs, distinct cellular membrane, nuclear size variation, and high nuclear grade, were also associated with HER2 amplification in non-IHC 2 + cases, demonstrating their predictive value as complements to IHC. In conclusion, we provide specific morphologic features that will improve pathologist performance in identifying more HER2-positive BCs. We further suggest an algorithm for trastuzumab therapy decisions using a combination of histomorphologic evaluation and the updated 2018 guidelines.

Reappraisal of HER2 Amplification in High-Grade Urothelial Carcinoma Based on 2018 ASCO/CAP Clinical Practice Guidelines

OBJECTIVES

To examine and compare human epidermal growth factor receptor 2 (HER2) amplification status in high-grade urothelial carcinoma (HGUCa), using both 2013 and 2018 HER2 reporting guidelines for breast carcinoma from the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP).

METHODS

HER2 status by fluorescence in situ hybridization (FISH) assay in 78 cases of HGUCa was compared using 2013 and 2018 HER2 reporting guidelines.

RESULTS

HER2 amplification was observed in 22 (28.2%) of 78 tumors, of which 17 were in group 1, 1 in group 2, and 2 each in groups 3 and 4 (FISH assay, 2018). The remaining 14 HER2-amplified tumors (FISH assay, 2013) became negative, falling into group 2 (FISH assay, 2018) and were either negative or equivocal on immunohistochemistry (IHC, 2018). All FISH-negative tumors (n = 37) using 2013 criteria remained negative (group 5, 2018). FISH-equivocal tumors (2013) were further categorized into HER2 amplified (n = 1) and HER2 negative (n = 4) (2018). Overall, 20 (25.6%) tumors had discordant HER2 FISH results (2018 vs 2013).

CONCLUSIONS

Implementing 2018 guidelines, HER2 amplification decreased from 36 to 22 cases. The group with a HER2/CEP17 ratio of 2 or more and average HER2 copy number less than 4 (group 2) were predominantly negative by IHC, suggesting a biologically distinct group of HGUCa that is different from HER2-amplified tumors, which may not respond to HER2-targeted therapy.

Retracted: Microcalcification-associated breast cancer: HER2-enriched molecular subtype is associated with mammographic features

OBJECTIVE

To investigate whether the mammographic features were different between breast cancer HER2-enriched molecular subtype and non-HER2-enriched molecular subtype.

METHODS

283 microcalcification-associated breast cancers were identified (HER2-enriched: n = 57; non-HER2-enriched: n = 226). Mammographic tumor mass and calcification features in relation to HER2 molecular subtype were analyzed.

RESULTS

On univariate analysis, HER2-enriched molecular subtype rates were significantly higher (a) in tumor size ≤2 cm [33 of 57 (57.9%)] than in tumor size >2 cm lesions [22 of 226 (9.7%)] (p = 0.007), (b) in non-spiculated mass [39 of 57 (68.4%)] than in spiculated mass lesions [18 of 226 (7.9%)] (p = 0.034)，(c) in calcifications extent >2 cm [41 of 57 (71.9%)] lesions than in calcifications extent ≤2 cm lesions [16 of 226 (7.1%)] (p < 0.001) and (d) in calcification density ＞20 cm-2 [44 of 57 (71.2%)] lesions than in calcification density ≤20 cm-2 lesions [13 of 226 (5.8%)] (p = 0.034).On multivariate analysis, three mammographic features [tumor size >2 cm vs size ≤2 cm odds ratio (OR): 0.415 95% confidence interval (CI) (0.215 to 0.802), p = 0.009, spiculated mass vs non-spiculated mass OR: 0.226 95% CI (0.114 to 0.446), p < 0.001 and calcifications extent >2 cm vs calcifications extent ≤2 cm OR: 7.754, 95% CI (3.100 to 19.339) p< 0.001] were independent predictors. Our results indicated that small tumor size, non-spiculated mass and calcification extent >2 cm are more likely to be HER2 molecular subtype. The discrimination of this model, as quantified by the area under the curve, was 0.751 [95% CI (0.701 to 0.854)].

CONCLUSION

Our study presents a prediction model that incorporates the mammographic features of tumor size, non-spiculated mass and calcification extent, which can potentially be used to preoperative predict breast cancer HER2-enriched subtype.

ADVANCES IN KNOWLEDGE

Mammographic features can noninvasively visualize breast tumor phenotype characteristics.

Rapid HER2 cytologic fluorescence in situ hybridization for breast cancer using noncontact alternating current electric field mixing

BACKGROUND

Human epidermal growth factor receptor 2-in situ hybridization (HER2-ISH) is widely approved for diagnostic, prognostic biomarker testing of formalin-fixed paraffin-embedded tissue blocks. However, cytologic ISH analysis has a potential advantage in tumor samples such as pleural effusion and ascites that are difficult to obtain the histological specimens. Our aim was to evaluate the clinical reliability of a novel rapid cytologic HER2 fluorescence ISH protocol (rapid-CytoFISH).

MATERIALS AND METHODS

Using a new device, we applied a high-voltage/frequency, noncontact alternating current electric field to tissue imprints and needle rinses, which mixed the probe within microdroplets as the voltage was switched on and off (AC mixing). Cytologic samples (n = 143) were collected from patients with immunohistochemically identified HER2 breast cancers. The specimens were then tested using standard dual-color ISH using formalin-fixed paraffin-embedded tissue (FFPE-tissue DISH) for HER2-targeted therapies, CytoFISH, and rapid-CytoFISH (completed within 4 h).

RESULTS

All 143 collected cytologic specimens (50 imprinted cytology specimens from resected tumors and 93 liquid-based cytology specimens from needle rinses) were suitable for FISH analysis. The HER2/chromosome enumeration probe (CEP) 17 ratios did not significantly differ between FFPE-tissue DISH and either CytoFISH protocol. Based on HER2 scoring criteria, we found 95.1% agreement between FFPE-tissue DISH and CytoFISH (Cohen's kappa coefficient = 0.771 and 95% confidence interval (CI): 0.614-0.927).

CONCLUSION

CytoFISH could potentially serve as a clinical tool for prompt determination of HER2 status in breast cancer cytology. Rapid-CytoFISH with AC mixing will enable cancer diagnoses and HER2 status to be determined on the same day a patient comes to a clinic or hospital.

HER2 Testing for Breast Cancer in the Genomics Laboratory: A Sea Change for Fluorescence In Situ Hybridization

CONTEXT.—

Guidelines for HER2 testing in breast cancer have changed over time, from the US Food and Drug Administration guideline to the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines published in 2007, 2013, and 2018.

OBJECTIVE.—

To investigate the change in assignment of HER2 status in breast cancers with equivocal (2+) immunohistochemistry (IHC) results by fluorescence in situ hybridization (FISH) following implementation of the ASCO/CAP 2018 guideline.

DESIGN.—

The study included 3556 invasive breast cancers that were HER2 equivocal (2+) by IHC and were submitted to our FISH laboratory after July 2018. Reflex testing (with repeat IHC staining) was performed on certain categories of FISH results known as groups 2, 3, and 4. Concomitant review of IHC and FISH was performed on these reflex cases per 2018 guideline recommendations. The FISH data were analyzed to compare US Food and Drug Administration and ASCO/CAP 2007, 2013, and 2018 interpretations.

RESULTS.—

Of 3548 invasive breast cancers with complete data available, the percentage agreement for FISH according to different guidelines was highest for ASCO/CAP 2018 versus US Food and Drug Administration (96.5%), followed by ASCO/CAP 2018 versus 2007 (93.8%), and lowest with ASCO/CAP 2018 versus 2013 (83.7%). Per the 2018 guideline, reflex IHC testing was performed on 633 breast cancers (17.8%); the majority of reflex testing results were negative (541 of 633; 85.5%). The overall distribution of HER2 FISH results (per the 2018 guideline) was 88.5% negative and 11.5% positive.

CONCLUSIONS.—

By eliminating the equivocal FISH category, the 2018 ASCO/CAP guideline significantly reduced the HER2 FISH-positive rate in tumors with equivocal (2+) IHC results.

Impact of the Updated 2018 American Society of Clinical Oncology/College of American Pathologists Guideline for Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer

CONTEXT.—

The updated American Society of Clinical Oncology/College of American Pathologists guideline for human epidermal growth factor receptor 2 (HER2) testing in breast cancer requires pathologists to re-evaluate HER2 status.

OBJECTIVE.—

To define HER2 status of breast cancer using immunohistochemistry and fluorescence in situ hybridization.

DESIGN.—

Diagnostic reports of invasive breast cancers made between 2014 and 2018 with HER2 immunohistochemistry and fluorescence in situ hybridization results were retrieved. HER2 status was re-defined using the updated recommendations.

RESULTS.—

Of 2514 tumors, 89.7% (2254 of 2514) suggested for fluorescence in situ hybridization assay were HER2 immunohistochemistry 2+. Approximately 8.9% (225 of 2514) and 1.4% (35 of 2514) of tumors were of immunohistochemistry 0/1+ and 3+, respectively. Based on the average HER2 copy number and HER2:CEP17 ratio, tumors were assigned into 5 groups, including 13.1% (330 of 2514) group 1 tumors, 2.1% (52 of 2514) group 2 tumors, 1.1% (27 of 2514) group 3 tumors, 7.0% (175 of 2514) group 4 tumors, and 76.8% (1930 of 2514) group 5 tumors. In combination with immunohistochemistry, all tumors in group 2 and group 4 changed HER2 status, from positive and equivocal into negative, respectively, while group 3 tumors remained positive. Comparative analyses of clinicopathologic features of tumors in different groups revealed that group 2 and 4 tumors displayed worse clinicopathologic features than those of group 5, while group 3 tumors shared similar clinicopathologic features to those of group 1.

CONCLUSIONS.—

Following the updated guideline, HER2 status is clearly designated. Significant differences regarding clinical features were observed between tumors in different groups but they share the same HER2 status, suggesting further validation of the accuracy of this diagnostic approach is warranted.

Clinicopathologic features of breast cancer reclassified as HER2-amplified by fluorescence in situ hybridization with alternative chromosome 17 probes

OBJECTIVE

Dual probe fluorescence in situ hybridization (FISH) assays for determination of human epidermal growth factor receptor 2 (HER2) gene amplification in breast cancer provide a ratio of HER2 to chromosome 17. The ratio may be skewed by copy number alterations (CNA) in the control locus for chromosome 17 (CEP17). We analyzed the impact of alternative chromosome 17 control probes on HER2 status in a series of breast cancers with an emphasis on patients reclassified as amplified.

METHODS

Breast cancer patients with equivocal HER2 immunohistochemistry (2+) and equivocal FISH with CEP17 were included. Reclassification of HER2 status was assessed with alternative chromosome 17 control probes (LIS1 and RARA).

RESULTS

A total of 40 unique patients with 46 specimens reflexed to alternative chromosome 17 probe testing were identified. The majority (>80%) of patients had pT1-2, hormone receptor-positive tumors with an intermediate or high combined histologic grade. There were 34/46 (73.9%) specimens reclassified as amplified with alternative probes, corresponding to 29/40 (72.5%) patients. Of the patients reclassified as amplified with alternative probes, 34.5% (10/29) received HER2-targeted therapy.

CONCLUSION

In this series, the majority of breast cancers tested with alternative chromosome 17 control probes under the 2013 ASCO/CAP Guidelines were converted to HER2-amplified. The treatment data and the clinicopathologic profile of the tumors suggest that most of these patients will neither receive nor benefit from HER2-targeted therapy. The findings support the recommendation in the 2018 ASCO/CAP HER2 Guidelines to discontinue the use of alternative chromosome 17 probes.

A clinicopathological study of 30 breast cancer cases with a HER2/CEP17 ratio of ≥2.0 but an average HER2 copy number of <4.0 signals per cell

The American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) have recently issued updated guidelines on human epidermal growth factor receptor 2 (HER2) testing by fluorescence in situ hybridization (FISH) in invasive breast cancers. Cases with a HER2/chromosome enumeration probe 17 (CEP17) ratio of ≥2.0 but an average HER2 copy number of <4.0 signals per cell (ISH group 2) are no longer automatically classified as ISH positive. Herein, 30 cases in ISH group 2 were collected. Another 100 patients with a HER2/CEP17 ratio <2.0 and <4.0 HER2 signals per cell (ISH group 5) and 100 patients with a HER2/CEP17 ratio of ≥2.0 and an average HER2 copy number of ≥4.0 signals per cell (ISH group 1) were also recruited for comparison. According to the 2018 ASCO/CAP guidelines, all the cases in ISH group 2 were categorized as HER2 negative. The clinicopathological characteristics of the patients in ISH group 2 were intermediate between ISH group 1 and group 5. Survival analyses revealed that there was no significant disease-free survival (DFS) and overall survival (OS) difference between patients with or without targeted therapy in ISH group 2, as well as between patients with targeted therapy in ISH group 1 and patients in ISH group 2. Patients without targeted therapy in ISH group 2 had a significantly worse OS than patients with targeted therapy in ISH group 1 and patients in ISH group 5. In conclusion, patients in ISH group 2 represent a biologically heterogeneous subset, which are different from those in ISH group 1 and 5. A larger cohort of patients in ISH group 2 should be included for future researches to define the efficacy of HER2-targeted therapy.

Applying the New Guidelines of HER2 Testing in Breast Cancer

PURPOSE OF REVIEW

The human epidermal growth factor receptor 2 (HER2) is an important prognostic and predictive biomarker in the breast cancer. The American Society of Clinical Oncology/College of American Pathology (ASCO/CAP) has published HER2 testing guidelines in breast cancer. We herein reviewed the HER2 testing guidelines in breast cancer with a focus on the application of the current guidelines.

RECENT FINDINGS

The continual investigation of HER2 testing in breast cancer has resulted in updates in the HER2 testing guidelines. The current guidelines focus on the uncommon clinical scenarios and emphasize the coordination between immunohistochemistry and in situ hybridization results, in an effort to improve clarity and accuracy. The ASCO/CAP guidelines provide valuable recommendations to ensure the accurate evaluation of HER2 status in breast cancer patients through standardization. Additional studies, particularly those with long-term outcome data are still needed to validate the guideline recommendations, especially the uncommon cases.

Impact of 2013 ASCO/CAP guidelines on various HER2 reporting categories in breast cancer by fluorescentin-situhybridization and Immunohistochemistry: A meta-analysis with systematic review

Objective:

The ASCO/CAP guidelines for reporting HER2 in breast cancer, first released in 2007, aimed to standardize the reporting protocol, and were updated in 2013 and 2018, to ensure right treatment. Several studies have analyzed the changes attributed to 2013 updated guidelines, and majority of them found increase in positive and equivocal cases. However, the precise implication of these updated guidelines is still contentious, in spite of the latest update (2018 guidelines) addressing some of the issues. We conducted systematic review and meta- analysis to see the impact of 2013 guidelines on various HER2 reporting categories by both FISH and IHC.

Materials and Methods:

After extensively searching the pertinent literature, 16 studies were included for the systematic review. We divided our approach in three strategies: (1) Studies in which breast cancer cases were scored for HER2 by FISH or IHC as a primary test concurrently by both 2007 and 2013 guidelines, (2) Studies in which HER2 results were equivocal by IHC and were followed by reflex-FISH test by both 2007 and 2013 guidelines, and (3) Studies in which trends of HER2 reporting were compared in the two periods before and after implementation of updated 2013 guidelines. All the paired data in these respective categories was pooled and analyzed statistically to see the overall impact of the updated guidelines.

Results:

In the first category, by pooled analysis of primary FISH testing there has been a significant increase in the equivocal cases (P< 0.001) and positive cases (P= 0.037). We also found 8.3% and 0.8% of all the negative cases from 2007 guidelines shifted to equivocal and positive categories, respectively. Similarly by primary IHC testing there has been a significant increase in both equivocal cases (P< 0.001) and positive cases (P= 0.02). In the second category of reflex-FISH testing there was a substantial increase in the equivocal cases (P< 0.0001); however there is insignificant decrease (10% to 9.7%;P= 0.66) in the amplified cases. In the third approach for evaluating the trend, with the implementation of 2013 guidelines, there was increase in the equivocal category (P= 0.025) and positive category (P= 0.0088) by IHC. By FISH test also there was significant increase in the equivocal category (P< 0.001) while the increase in the positive category was non-significant (P= 0.159).

Conclusions:

The updated 2013 guidelines has significantly increased the positive and equivocal cases using primary FISH or IHC test and with further reflex testing, thereby increasing the double equivocal cases and increasing the cost and delaying the decision for definite management. However, whether the additional patients becoming eligible for HDT will derive treatment benefit needs to be answered by further large clinical trials.

An updated evaluation of serum sHER2, CA15.3, and CEA levels as biomarkers for the response of patients with metastatic breast cancer to trastuzumab-based therapies

Background

The transmembrane receptor tyrosine kinase HER2 is overexpressed in approximately 15% of breast tumors and correlates with poor clinical prognosis. Several treatments that target HER2 are approved for treatment of HER2-positive metastatic breast cancer. The serum biomarkers most widely used to monitor anti-HER2 therapies in patients with HER2-positive metastatic breast cancer currently are CA15.3 and CEA. Nevertheless, their clinical utility in patients with breast cancer remains a subject of discussion and controversy; thus, additional markers may prove useful in monitoring the therapeutic responses of these patients. The extracellular domain of HER2 can be shed by proteolytic cleavage into the circulation and this shed form, sHER2, is reported to be augmented during metastasis of HER2-positive breast tumors. Here, we studied the clinical usefulness of sHER2, CA15.3, and CEA for monitoring treatment for breast cancer.

Methods

We measured prospectively pretreatment and post-treatment serum levels (day 1, 30, 60 and 90) of these three biomarkers in 47 HER2-positive, metastatic breast cancer patients treated with trastuzumab in combination with paclitaxel. Evaluation of the disease was performed according to the Response Evaluation Criteria in Solid Tumor (RECIST) at day 90.

Results

Patients with progressive disease at day 90 had smaller relative changes between day 1 and day 30 than those with complete, partial or stable responses at day 90: -9% versus -38% for sHER2 (P = 0.02), +23% versus -17% for CA15.3 (P = 0.005) and +29% versus -26% for CEA (P = 0.02). Patients with progressive disease at day 90 were less likely than the other patients to have a relative decrease of > 20% in their biomarker levels at day 30: 6% vs 33% for sHER2 (P = 0.03), 0% vs 27% for CA15.3 (P = 0.03), 4% vs 29% for CEA (P = 0.04). No patient with progressive disease at day 90 had > 20% reduction of the average combined biomarker levels at day 30 whereas 63% of the other patients had (P = 0.003). Moreover, when we analyzed a > 10% reduction of the average biomarker levels no patient with progressive disease at day 90 had a decrease > 10% at day 30 whereas 78% of other patients had (P<0.001, Se = 100%, Sp = 78%).

Conclusion

We show that regular measurement of sHER2, CA15.3, and CEA levels is useful for predicting the therapeutic response and for monitoring HER2-targeted therapy in patients with HER2-positive metastatic breast cancer. The average decrease of the three biomarkers with a threshold of > 10% appears to be the best parameter to distinguish patients who go on to have progressive disease from those who will have a complete, partial or stable response.

Assessment of ERBB2/HER2 Status in HER2-Equivocal Breast Cancers by FISH and 2013/2014 ASCO-CAP Guidelines

Importance

The 2013/2014 American Society of Clinical Oncology and College of American Pathologists (ASCO-CAP) guidelines for HER2 testing by fluorescence in situ hybridization (FISH) designated an "equivocal" category (average HER2 copies per tumor cell ≥4-6 with HER2/CEP17 ratio <2.0) to be resolved as negative or positive by assessments with alternative control probes. Approximately 4% to 12% of all invasive breast cancers are characterized as HER2-equivocal based on FISH.

Objective

To evaluate the following hypotheses: (1) genetic loci used as alternative controls are heterozygously deleted in a substantial proportion of breast cancers; (2) use of these loci for assessment of HER2 by FISH leads to false-positive assessments; and (3) these HER2 false-positive breast cancer patients have outcomes that do not differ from clinical outcomes for patients with HER2-negative breast cancer.

Design, Setting, and Participants

We retrospectively assessed the use of chromosome 17 p-arm and q-arm alternative control genomic sites (TP53, D17S122, SMS, RARA, TOP2A), as recommended by the 2013/2014 ASCO-CAP guidelines for HER2 testing, in patients whose data were available through Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and whose tissues were available through the Breast Cancer International Research Group clinical trials. We used data from an international cohort database of invasive breast cancers (1980 participants) and international clinical trial of adjuvant chemotherapy in invasive, node-positive breast cancer patients.

Main Outcomes and Measures

The primary objectives were to (1) assess frequency of heterozygous deletions in chromosome 17 genomic sites used as FISH internal controls for evaluation of HER2 status among HER2-equivocal cancers; (2) characterize impact of using deleted sites for determination of HER2-to-internal-control-gene ratios; (3) assess HER2 protein expression in each subgroup; and (4) compare clinical outcomes for each subgroup.

Results

Of the 1980 patients in METABRIC,1915 patients were fully evaluated. In addition, 100 HER2-equivocal breast cancers by FISH and 100 comparator FISH-negative breast cancers from the BCIRG-005 trial were analyzed. Heterozygous deletions, particularly in specific p-arm sites, were common in both HER2-amplified and HER2-not-amplified breast cancers. Use of alternative control probes from these regions to assess HER2 by FISH in HER2-equivocal as well as HER2-not-amplified breast cancers resulted in high rates of false-positive ratios (HER2-to-alternative control ratio ≥2.0) owing to heterozygous deletions of control p-arm genomic sites used in ratio denominators. Misclassification of HER2 status was observed not only in breast cancers with ASCO-CAP equivocal status but also in breast cancers with an average of fewer than 4.0 HER2 copies per tumor cell when using alternative control probes.

Conclusions and Relevance

The indiscriminate use of alternative control probes to calculate HER2 FISH ratios in HER2-equivocal breast cancers may lead to false-positive interpretations of HER2 status resulting from unrecognized heterozygous deletions in 1 or more of these alternative control genomic sites and incorrect HER2 ratio determinations.

Droplet digital polymerase chain reaction offers an improvisation over conventional immunohistochemistry and fluorescent in situ hybridization for ascertaining Her2 status of breast cancer

Background

Droplet digital polymerase chain reaction (DDPCR) is a recent modality for detecting Her2 expression which is quantitative, cheaper, easier to standardize, and free from interobserver variation.

Purpose

The purpose of this study is to incorporate DDPCR in the current diagnostic paradigm with clinical benefit.

Materials and Methods

Fifty-four consecutive patients were tested by immunohistochemistry (IHC), fluorescent in situ hybridization (FISH), and DDPCR. With FISH result as gold standard, receiver operating characteristic curves for DDPCR ratio were analyzed to label Her2-negative, equivocal, and positive cases as DDPCR score 1, 2, and 3, respectively. Proportion of patients labeled unequivocally as Her2 positive or negative was defined to have "clinically benefitted" from the test. Drawing parallel to inter-relationships between DDPCR, IHC, and FISH in the test cohort, four diagnostic pathways were defined - (1) initial IHC followed by FISH, (2) initial DDPCR followed by FISH, (3) initial IHC followed by DDPCR followed by FISH, and (4) initial DDPCR followed by IHC followed by FISH.

Results

Clinical benefit of DDPCR as an initial test in the test cohort was 57%, while it was 65% if used as a second-line test among those with an initial inconclusive IHC result. Sensitivity analysis in the simulation cohort revealed that if DDPCR cost was ≤0.6 times the cost of IHC, then a three-step pathway with DDPCR upfront would near certainly prove most cost beneficial. If DDPCR cost was >0.6 but ≤2 times the cost of IHC, then a three-step pathway with DDPCR as second-line test had a higher probability to prove most cost beneficial. If DDPCR cost was >2 times the cost of IHC, then conventional pathway had a higher probability to prove most cost-effective.

Conclusion

Incorporating DDPCR in the current clinical diagnostic paradigm has the potential to improve its cost-effectiveness and benefit.

The differences of clinicopathologic characteristics among subgroups of reclassified HER2 fluorescence in situ hybridization (FISH) according to the ASCO/CAP 2018 breast cancer HER2 testing guidelines

Aims

The aim of this study is to analyse differences in clinicopathologic features among reclassified human epidermal growth factor receptor-2 (HER2) fluorescence in situ hybridization (FISH) results in breast cancers according to 2018 guidelines.

Methods

According to different ratios of HER2 copy numbers to chromosome 17 centromere numbers (HER2/CEP17) and average HER2 copy numbers, 3795 invasive breast cancers were classified into six groups. Clinicopathologic features were collected and compared among different FISH groups.

Results

There were no statistically significant differences about HER2 positive rate between 2013 and 2018 guidelines (p=0.518). After re-evaluating these cases according to 2018 guidelines, the cases that converted to a HER2 positive status had clinicopathologic features similar to samples in group 1 (ratio ≥2.0, HER2 ≥4.0). Compared with group 5 (ratio <2.0, HER2 <4.0), the cases in groups 1 had higher histological grade, more frequent occurrence of negative oestrogen receptor and progesterone receptor status and a higher Ki67 index. The samples in group 4 (ratio <2.0, 4.0≤HER2<6.0) showed a higher histological grade and higher Ki67 index than did the samples in group 5 but had a lower histological grade and lower Ki67 index than did the samples in group 1a (ratio ≥2.0, HER2 ≥6.0).

Conclusion

Different categories of HER2 FISH test results have significant differences in clinicopathologic features. With no equivocal cases in 2018 HER2 guidelines, the clear division of HER2 status is helpful for making treatment recommendations about HER2 targeted therapy.

Impact of the 2018 ASCO/CAP guidelines on HER2 fluorescence in situ hybridization interpretation in invasive breast cancers with immunohistochemically equivocal results

The American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) recently issued updated guidelines on human epidermal growth factor receptor 2 (HER2) testing by fluorescence in situ hybridization (FISH) in invasive breast cancers. In this study, we aimed to investigate the impact of the new recommendations on HER2 FISH interpretation in invasive breast cancers with immunohistochemically (IHC) equivocal results. 1810 breast cancer cases with IHC equivocal results were enrolled in this study between January 2012 and May 2019. Concomitant IHC was performed on the same tissue blocks detected by FISH testing. According to the 2018 guidelines, all the cases in ISH group 2 were categorized as HER2 negative; three of four cases in ISH group 3 were considered as HER2 positive, while the one scored IHC 1+ was reclassified as HER2 negative; Fifty-three previously ISH equivocal cases were redistributed into ten HER2-positive cases and forty-three HER2-negative cases. In conclusion, the utility of 2018 ASCO/CAP guidelines resulted in a slight decrease in HER2 positive rate, due to the reclassification of cases in ISH group 2 and group 4. The implementation of the new guidelines can reduce reflex FISH test and make the diagnosis of HER2 gene status more definitive.

Implementation of the 2018 American Society of Clinical Oncology/College of American Pathologists Guidelines on HER2/neu Assessment by FISH in breast cancers: predicted impact in a single institutional cohort

The 2018 American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP) update modified the interpretation guidelines for human epidermal growth factor receptor 2 (HER2) testing by incorporating immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) results in a subset of cases. Importantly, the new guidelines eliminate "equivocal" results, as well as the use of alternative chromosome 17 probes as the primary strategy for resolving the indeterminate FISH results. Herein, we investigate the predicted impact of implementing the 2018 ASCO/CAP guidelines on HER2 assessment by FISH in breast cancers, using data from a single institution. We compared the HER2 status of 1542 consecutive cases of breast carcinoma, interpreted by 2013 and 2018 ASCO/CAP guidelines. In total, 10.7% (165/1542) of the cases had a different final interpretation by 2018 guidelines compared with 2013 guidelines, including 70 previously HER2-positive cases reclassified as negative, four previously negative cases reclassified as positive, and 91 previously equivocal cases reclassified as negative. Overall, the number of HER2-positive cancers was reduced by 66 cases (4.3% reduction in the HER2 positivity rate). The newly HER2-negative cases were mostly estrogen receptor positive (90%), progesterone receptor positive (80%), stage 1 (60.9%), and grade 1-2 (59.4%) cancers; 70% of them had been designated as HER2 positive only after the use of an alternative chromosome 17 FISH probe after an intially equivocal result from the standard CEP17 probe. Overall, implementing the revised 2018 HER2 guidelines is predicted to change the HER2 results of 10.7% of breast cancers, mainly by reclassifying previously equivocal to negative results.

American Society of Clinical Oncology/College of American Pathologists 2018 Focused Update of Breast Cancer HER2 FISH Testing GuidelinesResults From a National Reference Laboratory

OBJECTIVES

To review impact of the ASCO/CAP 2018 update on HER2 testing.

METHODS

HER2 fluorescence in situ hybridization (FISH) test requests from primary and metastatic breast cancers between August 2018 and January 2019 were included. FISH results requiring a changed algorithm under the new guidelines (groups 2, 3, and 4) were identified and HER2:CEN17 ratios, average HER2, CEN17 signals/cell, and HER2 immunohistochemistry (IHC) results were recorded.

RESULTS

Of the HER2 FISH cases 176/812(21.7%) fell within groups 2, 3, or 4; 0/12, 1/12, and 2/152 cases were positive (3+) by IHC, and 1/12, 2/12, and 6/152 cases were positive after targeted scoring from groups 2, 3, and 4, respectively. Following 2018 updates, 8.3%, 25%, and 5.3% of the groups 2, 3, and 4 were positive, respectively.

CONCLUSIONS

Groups 2, 3, and 4 constituted over 20% of HER2 FISH tests in a reference laboratory. The 2018 ASCO/CAP update significantly decreased the HER2 positivity rate.

Quantitative assessments and clinical outcomes in HER2 equivocal 2018 ASCO/CAP ISH group 4 breast cancer

We quantified human epidermal growth factor receptor 2 (HER2) RNA and protein expression in 2018 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) in situ hybridization (ISH) group 4 (HER2/centromeric probe 17 (CEP17) ratio <2.0, average HER2 copy number ≥4.0 and <6.0, and 2013 ASCO/CAP ISH equivocal) breast cancers. Breast cancers in 2018 ASCO/CAP ISH group 4 between 2014 and 2017 were identified from the Yale archives. Sixty-three patients (34 with HER2 immunohistochemistry (IHC) 0/1+ and 29 with HER2 IHC 2+) were included. We compared patient characteristics, systemic treatments, and outcomes. We assessed HER2 by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and quantitative immunofluorescence (QIF). Among ISH group 4 cancers, higher HER2 mRNA (P < 0.0001) but similar HER2 protein levels were observed in IHC 2+ compared to IHC 0/1+ cancers. The distribution of RT-qPCR and QIF scores were independent of fluorescence in situ hybridization (FISH) ratio/copy number. Concordance between HER2 RT-qPCR and QIF was 69.8% (r = 0.52). Among 29 patients with IHC2+ results, 16 were HER2 positive by RT-qPCR and 12 were HER2 positive by QIF. Systemic treatment, recurrence, and survival outcomes were comparable among ISH group 4 cancers regardless of IHC 0/1+ or 2+ results. ISH group 4 cancers appear to form a distinct group with intermediate levels of RNA/protein expression, close to positive/negative cut points. Therefore, adjudication into positive or negative categories may not be meaningful. Our results support the 2018 ASCO/CAP recommendation to refrain from routine additional testing of these samples. Additional outcome information after trastuzumab treatment for patients in this special group might help to guide treatment decisions in these patients.

The Dilemma of HER2 Double-equivocal Breast Carcinomas: Genomic Profiling and Implications for Treatment

Supplemental Digital Content is available in the text.

The American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2013 guidelines for HER2 assessment have increased the number of HER2 equivocal breast carcinomas following in situ hybridization reflex testing, that is, HER2 “double equivocal” (equivocal protein expression and equivocal gene copy number). Forty-five double-equivocal carcinomas were subjected to Prosigna analysis. Twenty-seven cases were investigated for the expression of genes found to be differentially expressed between estrogen receptor (ER)-positive/HER2-positive (N=22) and ER-positive/HER2-negative (N=22) control cases. Twenty-nine of the 45 cases were also analyzed by targeted sequencing using a panel of 14 genes. We then explored the pathologic complete response rates in an independent series of double-equivocal carcinoma patients treated with trastuzumab-containing chemotherapy. All cases were ER-positive, with a mean Ki67 of 28%. Double-equivocal carcinomas were predominantly luminal B (76%); 9 cases (20%) were luminal A, and 2 cases (4%) HER2-enriched. The majority (73%) showed a high risk of recurrence by Prosigna, even when the carcinomas were small (<2 cm), node-negative/micrometastatic, and/or grade 2. Double-equivocal carcinomas showed TP53 (6/29, 20%), PIK3CA (3/29, 10%), HER2 (1/29, 3%), and MAP2K4 (1/29, 3%) mutations. Compared with grade-matched ER-positive/HER2-negative breast carcinomas from METABRIC, double-equivocal carcinomas harbored more frequently TP53 mutations and less frequently PIK3CA mutations (P<0.05). No significant differences were observed with grade-matched ER-positive/HER2-positive carcinomas. Lower pathologic complete response rates were observed in double-equivocal compared with HER2-positive patients (10% vs. 60%, P=0.009). Double-equivocal carcinomas are preferentially luminal B and show a high risk of recurrence. A subset of these tumors can be labeled as HER2-enriched by transcriptomic analysis. HER2 mutations can be identified in HER2 double-equivocal cases.

A Roundtable Discussion of the Breast Cancer Therapy Expert Group (BCTEG): Clinical Developments and Practice Guidance on Human Epidermal Growth Factor Receptor 2 (HER2)-positive Breast Cancer

Expression of human epidermal growth factor receptor 2 (HER2) in breast cancer defines a subset of patients (∼15%-20%) who are candidates for anti-HER2 therapies, most notably, trastuzumab, pertuzumab, antibody drug conjugates (eg, T-DM1), and tyrosine kinase inhibitor (TKI) drugs (eg, lapatinib and neratinib), all of which have dramatically changed the prognosis for this aggressive subtype of breast cancer. A roundtable meeting of the Breast Cancer Therapy Expert Group (BCTEG) was convened in March 2018 in an effort to discuss and clarify, from the perspective of the practicing community oncologist, recent developments in the diagnosis and treatment of HER2-positive (HER2⁺) breast cancer. Members of the group selected 4 key topics for discussion prior to the meeting, including diagnosis of HER2⁺ disease, and its treatment in the neoadjuvant, adjuvant, and metastatic settings. Approved testing methods, such as immunohistochemistry and fluorescence in situ hybridization, are used to demonstrate overexpression and/or amplification of HER2 in breast tumors, and established clinical guidelines are used to appropriately define treatment plans for patients with HER2⁺ disease. The panel acknowledges a range of treatment options now available for treatment of HER2⁺ breast cancer in the neoadjuvant, adjuvant, and advanced/metastatic settings, although it is noted that many controversies remain, including the optimal sequence of therapies, the most appropriate treatment(s) for subsets of patients with HER2⁺ disease (eg, hormone receptor-negative or -positive/HER2⁺), and uncertainties surrounding the diagnosis and definition of HER2⁺ disease. The current report summarizes the discussion of the BCTEG panel on this topic.

Assessing the impact of the 2018 American Society of Clinical Oncology/College of American Pathologists recommendations on human epidermal growth factor receptor 2 testing by fluorescence in situ hybridization in breast carcinoma

The American Society of Clinical Oncology/College of American Pathologists recently updated their recommendations on human epidermal growth factor receptor 2 (HER2) testing by fluorescence in situ hybridization (FISH) in invasive breast cancer, with a focus on the clarification of less common test patterns of ISH. We assessed the impact of the updated ASCO/CAP guidelines on 1044 FISH tested tumors by comparing categorization according to the 2007, 2013, and 2018 ISH classification criteria. The 2013 guidelines increased the number of positive cases (17.4% vs 10.7%) identifying 70 (6.7%) additional patients who met the eligibility criteria for consideration for HER2-targeted therapy compared with the 2007 guidelines. There was a reduction in equivocal tumors (7.7%) with tumors classified as equivocal by the 2007 guidelines (n = 136) redistributed into positive (74, 54.4%) and negative (49, 36.0%) groups. The 2018 guidelines reclassified 10.8% of tumors in our series with a reduction in the number of positive tumors (7.1%). While the proportion of positive tumors (10.2%) was similar to that in 2007 (10.7%), the composition of this group was significantly altered. HER2 equivocal cases, a group which under the 2013 guidelines caused diagnostic and treatment difficulties, were largely eliminated. Our findings suggest that the 2018 update represents a potentially significant change in therapeutic options for a substantial proportion of patients with 2.9% of FISH-positive tumors according to the 2007 and 2013 guidelines now categorized as HER2 negative and, thus, ineligible for HER2-targeted therapy.

MicroRNA-16 sensitizes drug-resistant breast cancer cells to Adriamycin by targeting Wip1 and Bcl-2

Clinical evidence indicates that drug resistance is a major obstacle in the treatment of breast cancer (BC). Drug resistance results in the disease being uncontrollable, and leads to high mortality rates. The aim of the present study was to investigate the chemosensitizing effect of microRNA (miR)-16 on Adriamycin (ADM)-resistant BC cells and the associated mechanisms. BC tumors from 40 patients were collected and reverse transcription-quantitative PCR was used to examine the expression of miR-16. ADM-sensitive (MCF-7/S) and -resistant (MCF-7/A) BC cell lines were used to determine the expression of miR-16 prior to and following transfection with miR-16 mimics or inhibitor. The effects of increased and decreased miR-16 expression on the chemosensitivity of BC cells to ADM was analyzed using MTT, colony survival and flow cytometry assays. miR-16 was found to regulate wild-type p53-induced phosphatase 1 (Wip1) and Bcl-2 expression, as confirmed by western blotting, immunofluorescence staining and luciferase reporter assays. miR-16 expression in drug-resistant tumor tissues and cells was decreased, compared with that the drug-sensitive equivalents. Overexpression of miR-16 in MCF-7/A was associated with a sharp downregulation of Wip1 and Bcl-2 expression, leading to increased ADM-induced cell apoptosis and sensitization of MCF-7/A cells to ADM treatment. Taken together, the results demonstrate that miR-16 may serve as an effective chemosensitizing target to enhance the effects of chemotherapy in drug-resistant BC cells with high Wip1 and Bcl-2 expression. This provides a novel approach to improving the chemotherapeutic efficacy in drug-resistant BC via regulation of miRs.

What to expect from the 2018 ASCO/CAP HER2 guideline in the reflex in situ hybridization test of immunohistochemically equivocal 2+ cases?

To evaluate the effect of the 2018 ASCO/CAP guideline in the identification of HER2-positive breast carcinomas (BC) in reflex in situ hybridization (ISH) test. A total of 592 primary invasive BC cases from before and after the publication of the updated ASCO/CAP guideline were evaluated for HER2 amplification by silver ISH according to the 2013 and 2018 guidelines. Cases were mostly (95%) HER2 equivocal by immunohistochemistry (IHC), not centrally reviewed. Other reasons for referring cases were IHC confirmation, IHC discordancy (either between needle-core-biopsy (NCB) and surgical excision specimen (SES) or between different laboratories) and IHC result unexpected for histopathologic features. Cases evaluated with the 2013 guideline (1st cohort) were 14.6% HER2-positive, decreasing significantly after the reclassification with the 2018 guideline due to the exclusion of group 2 cases without HER2 protein overexpression. Cases studied after the implementation of the 2018 guideline (2nd cohort) were 8.7% HER2-positive, a frequency that was not significantly different from the reclassification of the 1st cohort with the 2018 guideline. All cases referred for IHC confirmation had the expected ISH result. Cases with IHC discordancy between NCB and SES were ISH concordant. Only one out of 14 cases with an IHC score 3+ and classified as histological grade 1 or with a Ki67 below 10% was classified as ISH HER2-positive. The 2018 ASCO/CAP guideline resulted in a decrease of HER2-positive cases in reflex ISH test, selecting less patients for anti-HER2-targeted therapy.

Effect of Trastuzumab among HER2-Positive Breast Cancer Patients that Achieved Pathologic Complete Response after Neoadjuvant Chemotherapy

Background

We sought to investigate the incremental benefit of trastuzumab in patients with HER2-positive breast cancer who achieved a pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT).

Methods

The data of HER2-positive invasive breast cancer patients treated with NACT and achieving pCR were obtained from the institutional database. Patients were categorized according to trastuzumab administration. The Kaplan-Meier method and log-rank estimates were used to test the association between trastuzumab administration and survival. Univariate and multivariate Cox regressions were used to obtain hazard ratios.

Results

Of 223 patients, 83 (37.2%) were treated with NACT without trastuzumab and 140 (62.8%) were treated with NACT plus trastuzumab for 1 year. After a median follow-up of 67 months, the trastuzumab group showed improved relapse-free survival compared with the no-trastuzumab group (95.7 vs. 87.8%, hazard ratio = 0.31, p = 0.028). No significant difference in distant disease-free survival or overall survival was observed (p = 0.250 and 0.432, respectively). Multivariate analysis identified endocrine therapy and trastuzumab administration to be associated with decreased risk of relapse (p = 0.018 and 0.030, respectively).

Conclusion

The administration of trastuzumab should be considered standard treatment for HER2-positive patients who have achieved pCR after NACT alone.

Breast cancers with a HER2/CEP17 ratio of 2.0 or greater and an average HER2 copy number of less than 4.0 per cell: frequency, immunohistochemical correlation, and clinicopathological features

The 2013 American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) guidelines classified breast cancers with a fluorescence in situ hybridization dual-probe HER2/CEP17 ratio of 2 or greater as "amplified," inclusive of cases with a HER2 copy number less than 4. The 2018 ASCO/CAP update assigns HER2/neu status for the latter group in a fashion that is highly dependent on the associated immunohistochemical findings. Herein, the authors define the frequency, immunohistochemical correlates, and other clinicopathological features of breast cancers with HER2/CEP17 ratio of 2 or greater and HER2/neu copy number less than 4 (group A), based on an analysis of an institutional cohort assessed for HER2/neu status by both florescence in situ hybridization and immunohistochemistry and scored using 2013 ASCO/CAP criteria. Group A cases were compared with a group B of HER2/neu-amplified breast cancers with a HER2/neu copy number of 4 or greater regarding a variety of clinicopathological features. One hundred sixty-nine (14%) of 1201 cases were HER2/neu amplified, 18 (10.7%) in group A and 151 (89.3%) in group B. By immunohistochemistry, 61.1% of group A cases were HER2/neu negative, 7 (38.9%) were equivocal, and none were positive. In contrast, 66.9% of group B cases were HER2 positive (3+). We could not demonstrate statistically significant differences between the 2 groups regarding standard clinicopathological variables. In summary, our group A cases account for 1.5% of breast cancers, and 10.7% of all HER2/neu-amplified cancers classified as such based on 2013 ASCO/CAP criteria. They are predominantly HER2/neu negative by immunohistochemistry, which suggests that they are biologically different from classically HER2/neu-amplified cases and which validates the 2018 ASCO/CAP guideline against automatically classifying such cases as HER2/neu amplified.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update

PURPOSE.—

To update key recommendations of the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline.

METHODS.—

Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations.

RECOMMENDATIONS.—

Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in >10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended workup for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥2.0; average HER2 copy number <4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio <2.0; average HER2 copy number ≥4.0 and <6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results.

Ancillary Prognostic and Predictive Testing in Breast Cancer: Focus on Discordant, Unusual, and Borderline Results

Ancillary testing in breast cancer has become standard of care to determine what therapies may be most effective for individual patients with breast cancer. Single-marker tests are required on all newly diagnosed and newly metastatic breast cancers. Markers of proliferation are also used, and include both single-marker tests like Ki67 as well as panel-based gene expression tests, which have made more recent contributions to prognostic and predictive testing in breast cancers. This review focuses on pathologist interpretation of these ancillary test results, with a focus on expected versus unexpected results and troubleshooting borderline, unusual, or discordant results.

Intrinsic molecular subtypes of breast cancers categorized as HER2-positive using an alternative chromosome 17 probe assay

The 2013 update of the American Society of Clinical Oncology-College of American Pathologists (ASCO-CAP) human epidermal growth factor receptor 2 (HER2) testing guidelines recommend using an alternative chromosome 17 probe assay to resolve HER2 results determined to be equivocal by immunohistochemistry (IHC) or fluorescence in-situ hybridization (FISH). However, it is unclear if cases considered HER2-positive (HER2⁺) by the alternative probe method are similar to those classified as HER2⁺ by traditional IHC and FISH criteria and benefit the same from HER2-targeted therapies. We studied the clinical and pathologic features of all 31 breast cancers classified as HER2⁺ by the alternative probe method at our institution since 2013 and determined their PAM50 intrinsic molecular subtypes. For comparison, we analyzed 19 consecutive cases that were classified as HER2⁺ by traditional FISH criteria during the same time period. Thirty (97%) cancers in the alternative probe cohort were estrogen receptor (ER)-positive (ER⁺), while only 9/19 (47%) of traditional HER2 controls were ER⁺ (p = 0.0002). Sufficient tissue for intrinsic subtype analysis was available for 20/31 cancers in the alternative probe cohort and 9/19 in the traditional HER2⁺ group. None (0%) of the 20 alternative probe-positive cases were of the HER2-enriched intrinsic subtype, while 8/9 (89%) of those HER2⁺ by traditional FISH criteria were HER2-enriched (p = 0.0001). These findings suggest that breast cancers classified as HER2⁺ only by the alternative probe method are biologically distinct from those classified as HER2⁺ by traditional criteria, and raises questions as to whether or not they derive the same benefit from HER2-targeted therapies.

Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update

Purpose To update key recommendations of the American Society of Clinical Oncology/College of American Pathologists human epidermal growth factor receptor 2 (HER2) testing in breast cancer guideline. Methods Based on the signals approach, an Expert Panel reviewed published literature and research survey results on the observed frequency of less common in situ hybridization (ISH) patterns to update the recommendations. Recommendations Two recommendations addressed via correspondence in 2015 are included. First, immunohistochemistry (IHC) 2+ is defined as invasive breast cancer with weak to moderate complete membrane staining observed in > 10% of tumor cells. Second, if the initial HER2 test result in a core needle biopsy specimen of a primary breast cancer is negative, a new HER2 test may (not "must") be ordered on the excision specimen based on specific clinical criteria. The HER2 testing algorithm for breast cancer is updated to address the recommended work-up for less common clinical scenarios (approximately 5% of cases) observed when using a dual-probe ISH assay. These scenarios are described as ISH group 2 ( HER2/chromosome enumeration probe 17 [CEP17] ratio ≥ 2.0; average HER2 copy number < 4.0 signals per cell), ISH group 3 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 6.0 signals per cell), and ISH group 4 ( HER2/CEP17 ratio < 2.0; average HER2 copy number ≥ 4.0 and < 6.0 signals per cell). The diagnostic approach includes more rigorous interpretation criteria for ISH and requires concomitant IHC review for dual-probe ISH groups 2 to 4 to arrive at the most accurate HER2 status designation (positive or negative) based on combined interpretation of the ISH and IHC assays. The Expert Panel recommends that laboratories using single-probe ISH assays include concomitant IHC review as part of the interpretation of all single-probe ISH assay results. Find additional information at www.asco.org/breast-cancer-guidelines .

The extracellular domain of Her2 in serum as a biomarker of breast cancer

Breast cancer is a major health problem worldwide. In ~15% of breast cancers, the epidermal growth factor receptor HER2, a transmembrane protein, is overexpressed. This HER2 overexpression is associated with an aggressive form of the disease and a poor clinical prognosis. The extracellular domain (ECD) of HER2 is released into the blood by a proteolytic mechanism known as "ECD shedding". This proteolytic shedding leaves a constitutively active truncated receptor in the membrane that is 10-100-fold more oncogenic than the full-length receptor and promotes the growth and survival of cancer cells. Shedding of the HER2 ECD is increased during metastasis: whereas 15% of primary breast cancer patients have elevated levels of serum HER2 ECD (sHER2 ECD), the levels reach 45% in patients with metastatic disease. Thus, sHER2 ECD has been proposed as a promising biomarker for cancer recurrence and for monitoring the disease status of patients overexpressing HER2. Nevertheless, in 2016, the American Society of Clinical Oncology advises clinicians not to use soluble HER2 levels to guide their choice of adjuvant therapy for patients with HER2-positive breast cancer, because the evidence was considered not strong enough. Currently, biomarkers such as carcinoembryonic antigen and cancer antigen 15-3 are widely used to monitor metastatic breast cancer disease even if the level of evidence of clinical impact of this monitoring is poor. In this article, we review the evidence that sHER2 ECD might be used in some situations as a biomarker for breast cancer. Although this serum biomarker will not replace the direct measurement of tumor HER2 status for diagnosis of early-stage tumors; it might be especially useful in metastatic disease for prognosis, as an indicator of cancer progression and of therapy response, particularly to anti-HER2 therapies. Owing to these data, sHER2 ECD should be considered as a promising biomarker to detect cancer recurrence and metastasis.

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.