References

Trastuzumab deruxtecan in previously treated HER2-low advanced breast cancer

10.1056/nejmoa2203690 · 2022 · External reference

Trastuzumab deruxtecan after endocrine therapy in metastatic breast cancer (DESTINY-Breast06)

10.1056/nejmoa2407086 · 2024 · External reference

HER2-low breast cancer: pathological and clinical landscape

10.1200/jco.19.02488 · 2020 · External reference

Human epidermal growth factor receptor 2 testing in breast cancer: ASCO/CAP clinical practice guideline focused update

10.5858/arpa.2018-0902-sa · 2018 · External reference

Clinical and molecular characteristics of HER2-low-positive breast cancer: pooled analysis of individual patient data from four prospective neoadjuvant clinical trials

10.1016/s1470-2045(21)00301-6 · 2021 · External reference

Clinical, pathological, and PAM50 gene expression features of HER2-low breast cancer

10.1038/s41523-020-00208-2 · 2021 · External reference

Human epidermal growth factor receptor 2 testing in breast cancer: ASCO-College of American Pathologists guideline update

10.1200/jco.22.02864 · 2023 · External reference

The PRISMA 2020 statement: an updated guideline for reporting systematic reviews

10.1136/bmj.n71 · 2021 · External reference

The development of a quality appraisal tool for studies of diagnostic reliability (QAREL)

10.1016/j.jclinepi.2009.10.002 · 2010 · External reference

The measurement of observer agreement for categorical data

10.2307/2529310 · 1977 · External reference

Interobserver and interassay concordance in HER2 immunohistochemistry: implications on HER2-low breast cancer

10.1097/pai.0000000000001281 · 2026 · External reference

Accuracy of human epidermal growth factor receptor 2 (HER2) immunohistochemistry scoring by pathologists in breast cancer, including the HER2-low cutoff

10.1186/s13000-025-01624-3 · 2025 · External reference

Prevalence and concordance of HER2-low and HER2-ultralow status between historical and rescored results in a multicenter study of breast cancer patients in China

10.1186/s13058-025-02001-0 · 2025 · External reference

Interobserver variability in HER2 breast biomarker reporting: implications for diagnostic consistency and treatment precision

2025 · External reference

Evaluating HER2 amplification and overexpression in breast cancer

10.1002/path.971 · 2001 · External reference

HER-2/neu in breast cancer: interobserver variability and performance of immunohistochemistry with 4 antibodies compared with fluorescent in situ hybridization

10.1038/modpathol.3880440 · 2001 · External reference

High interobserver agreement in immunohistochemical evaluation of HER-2/neu expression in breast cancer: a multicenter GEFPICS study

10.1016/j.ejca.2006.06.020 · 2006 · External reference

What causes discrepancies in HER2 testing for breast cancer? A Japanese ring study in conjunction with the global standard

10.1309/ajcp5uumfma5zkii · 2008 · External reference

Trainable immunohistochemical HER2/neu image analysis: a multisite performance study using 260 breast tissue specimens

10.5858/2010-0418-oar1.1 · 2011 · External reference

Accuracy and reproducibility of HER2 status in breast cancer using immunohistochemistry: a quality control study in Tuscany evaluating the impact of updated 2013 ASCO/CAP recommendations

10.1007/s12253-014-9852-0 · 2015 · External reference

Interobserver agreement in reporting HER2 Neu protein over expression by immunohistochemistry

10.4103/0377-4929.134663 · 2014 · External reference

Interobserver variability in HER-2/neu reporting on immunohistochemistry in breast carcinomas

2014 · External reference

Reproducibility of HER-2/neu overexpression with HERCEP test in invasive ductal breast cancer

2002 · External reference

Interobserver and interantibody reproducibility of HER2 immunohistochemical scoring in an enriched HER2-low-expressing breast cancer cohort

10.1093/ajcp/aqac184 · 2023 · External reference

Multi-institutional assessment of pathologist scoring HER2 immunohistochemistry

10.1016/j.modpat.2022.100032 · 2023 · External reference

Interobserver reproducibility of HER2 immunohistochemical assessment and concordance with fluorescent in situ hybridization (FISH): pathologist assessment compared to quantitative image analysis

10.1186/1471-2407-9-165 · 2009 · External reference

Interobserver reproducibility for HER2/neu immunohistochemistry: a comparison of reproducibility for the HercepTest and the 4B5 antibody clone

10.1016/j.prp.2015.11.016 · 2016 · External reference

Evaluation of HER-2/neu immunohistochemical assay sensitivity and scoring on formalin-fixed and paraffin-processed cell lines and breast tumors: a comparative study involving results from laboratories in 21 countries

10.1309/97wn-w6ux-xjwt-02h2 · 2002 · External reference

Distinguishing score 0 from score 1+ in HER2 immunohistochemistry-negative breast cancer: clinical and pathobiological relevance

10.1309/ajcp4a7ktayhzsoe · 2013 · External reference

A testing algorithm for determination of HER2 status in patients with breast cancer

2002 · External reference

Enhanced accuracy and reliability of HER-2/neu immunohistochemical scoring using digital microscopy

10.1309/y73u8x72b68tmgh5 · 2004 · External reference

Predicting the HER2 status of breast cancer from basic histopathology data: an analysis of 1500 breast cancers as part of the HER2000 International Study

10.1016/s0960-9776(02)00273-4 · 2003 · External reference

HER-2/neu protein expression in breast cancer evaluated by immunohistochemistry: a study of interlaboratory agreement

10.1309/980m-e24r-v19k-595d · 2000 · External reference

Practice of HER-2 immunohistochemistry in breast carcinoma in Austria

10.1007/s12253-008-9079-z · 2008 · External reference

Clinical laboratory assays for HER-2/neu amplification and overexpression: quality assurance, standardization, and proficiency testing

10.5858/2002-126-0803-clafhn · 2002 · External reference

Standardization of HER2 testing: results of an international proficiency-testing ring study

10.1038/modpathol.3800774 · 2007 · External reference

Interlaboratory concordance in HER2 testing: results of a Serbian ring-study

2019 · External reference

Bridging practice and precision: a quantitative HER2 protein assay ready for clinical use in guiding trastuzumab deruxtecan therapy

10.3389/fonc.2026.1747961 · 2026 · External reference

Interobserver agreement in scoring immunohistochemical overexpression of Her2 detected by five different antibodies on tissue microarrays of breast carcinomas

2007 · External reference

A global ring study: concordance between Ventana PATHWAY anti-HER2/neu (4B5) companion diagnostic assay and comparators in detecting HER2-low breast cancer

10.1016/j.modpat.2025.100867 · 2025 · External reference

Delineation of HER2 gene status in breast carcinoma by silver in situ hybridization is reproducible among laboratories and pathologists

10.2353/jmoldx.2008.080052 · 2008 · External reference

The role of artificial intelligence in accurate interpretation of HER2 immunohistochemical scores 0 and 1+ in breast cancer

10.1016/j.modpat.2022.100054 · 2023 · External reference

Systematic analysis of factors affecting human epidermal growth factor receptor 2 immunohistochemistry consistency, including ultralow expression

10.1016/j.labinv.2025.104134 · 2025 · External reference

Comparison of Dako HercepTest and Ventana PATHWAY anti-HER2 (4B5) tests and their correlation with fluorescent in situ hybridization in breast carcinoma

10.1097/pai.0000000000000646 · 2019 · External reference

Development of a deep-learning model tailored for HER2 detection in breast cancer to aid pathologists in interpreting HER2-low cases

10.1111/his.15274 · 2024 · External reference

Examination of pathologist-artificial intelligence interactions and their impact on pathologist accuracy using artificial intelligence-assisted scoring of immunohistochemistry for human epidermal growth factor receptor 2

10.5858/arpa.2025-0262-oa · 2026 · External reference

Observer performance in the use of digital and optical microscopy for the interpretation of tissue-based biomarkers

2014 · External reference

Fully automated artificial intelligence solution for human epidermal growth factor receptor 2 immunohistochemistry scoring in breast cancer

10.1200/po.24.00353 · 2024 · External reference

Using whole slide gray value map to predict HER2 expression and FISH status in breast cancer

10.3390/cancers14246233 · 2022 · External reference

Determining HER2 status by artificial intelligence: an investigation of primary, metastatic, and HER2 low breast tumors

10.3390/diagnostics13010168 · 2023 · External reference

Retrospective study to estimate the prevalence and describe the clinicopathological characteristics, treatments received and outcomes of HER2-low breast cancer

10.1016/j.esmoop.2023.101615 · 2023 · External reference

Analytical and clinical validation of PATHWAY HER2 (4B5) assay for HER2-ultralow breast cancer

10.1016/j.esmoop.2025.105310 · 2025 · External reference

Effects of the change in cutoff values for human epidermal growth factor receptor 2 status by immunohistochemistry and fluorescence in situ hybridization: a study comparing conventional brightfield microscopy, image analysis-assisted microscopy, and interobserver variance

10.5858/2010-0462-oar · 2011 · External reference

An evaluation of the impact of technical bias on the concordance rate between primary and recurrent tumors in breast cancer

10.1016/j.breast.2013.05.014 · 2013 · External reference

Agreement across 10 artificial intelligence models in assessing HER2 in breast cancer whole slide images

10.1016/j.modpat.2025.100944 · 2026 · External reference

HER2 status in breast cancer: experience of a Spanish National Reference Center

10.1007/s12094-011-0663-4 · 2011 · External reference

Free digital image analysis software helps to resolve equivocal scores in HER2 immunohistochemistry

10.1007/s00428-015-1868-7 · 2016 · External reference

Reading immunohistochemical slides on a computer monitor: a multisite performance study using 180 HER2-stained breast carcinomas

10.1097/pai.0b013e3181f5e84d · 2011 · External reference

A new rabbit monoclonal antibody (4B5) for the immunohistochemical (IHC) determination of the HER2 status in breast cancer: comparison with CB11, fluorescence in situ hybridization (FISH), and interlaboratory reproducibility

10.1097/pai.0b013e31802ced25 · 2007 · External reference

Implementation of a Canadian external quality assurance program for breast cancer biomarkers: an initiative of Canadian Quality Control in immunohistochemistry (cIQc) and Canadian Association of Pathologists (CAP) National Standards Committee/Immunohistochemistry

10.1097/pai.0b013e31819adacf · 2009 · External reference

A comparison study of HER2 protein overexpression and its gene status in breast cancer

2019 · External reference

Comparison of different approaches for assessment of HER2 expression on protein and mRNA level: prediction of chemotherapy response in the neoadjuvant GeparTrio trial

10.1007/s10549-010-1316-y · 2011 · External reference

What is the added value of digital image analysis of HER2 immunohistochemistry in breast cancer in clinical practice? A study with multiple platforms

10.1111/his.13812 · 2019 · External reference

Evaluating low HER2 status in invasive breast carcinoma via immunohistochemistry

10.1155/2023/9725647 · 2023 · External reference

Digital validation in breast cancer needle biopsies: comparison of scoring between pathologists’ microscopic and whole-slide-image assessments

10.3390/jpm14030312 · 2024 · External reference

Augmented interpretation of HER2, ER, and PR in breast cancer by artificial intelligence analyzer: enhancing interobserver agreement through a reader study of 201 cases

10.1186/s13058-024-01784-y · 2024 · External reference

HER2-low and ultralow expression of invasive breast carcinoma: clinicopathological features and immunohistochemical consistency analysis

10.1038/s41523-025-00872-2 · 2026 · External reference

AI microscope facilitates accurate interpretation of HER2 immunohistochemistry in breast cancer

10.1038/s41598-025-13820-8 · 2025 · External reference

Interobserver consistency and diagnostic challenges in HER2-ultralow breast cancer: a multicenter study

10.1016/j.esmoop.2024.104127 · 2025 · External reference

Reproducibility of immunohistochemical testing of estrogen receptors, progesterone receptors, human epidermal growth factor receptor-2 (HER2) and Ki-67 in Vietnam

10.3389/bjbs.2025.15455 · 2025 · External reference

Human epidermal growth factor receptor 2-low breast cancer: prevalence rate and scoring concordance among pathologists

10.1177/11782234251363664 · 2025 · External reference

HER2 testing on core needle biopsy specimens from primary breast cancers: interobserver reproducibility and concordance with surgically resected specimens

10.1186/1471-2407-10-534 · 2010 · External reference

Interobserver variation in the assessment of immunohistochemistry expression levels in HER2-negative breast cancer: can we improve the identification of low levels of HER2 expression by adjusting the criteria? An International Interobserver Study

10.1016/j.modpat.2022.100009 · 2023 · External reference

Development and validation of a HER2-low focused immunohistochemical scoring system with high-interobserver concordance: The Australian HER2-low breast cancer concordance study

10.1016/j.modpat.2024.100535 · 2024 · External reference

Interobserver agreement in scoring HER2-negative and HER2-low immunohistochemistry in breast cancer: reasons for discordance and impact of a single training session

10.1093/ajcp/aqaf043 · 2025 · External reference

Concordance of HER2-low scoring in breast carcinoma among expert pathologists in the United Kingdom and the republic of Ireland -on behalf of the UK national coordinating committee for breast pathology

10.1016/j.breast.2023.06.005 · 2023 · External reference

Concordance between pathologists and between specimen types in detection of HER2-low breast carcinoma by immunohistochemistry

10.1016/j.anndiagpath.2024.152288 · 2024 · External reference

Low interobserver agreement among subspecialised breast pathologists in evaluating HER2-low breast cancer

2024 · External reference

Examination of Low ERBB2 protein expression in breast cancer tissue

10.1001/jamaoncol.2021.7239 · 2022 · External reference

Immunohistochemical assessment of HER2 low breast cancer: interobserver reproducibility and correlation with digital image analysis

10.1007/s10549-024-07256-3 · 2024 · External reference

Independent Validation of a HER2-low focused immunohistochemistry scoring system for enhanced pathologist precision and consistency

10.1016/j.modpat.2024.100693 · 2025 · External reference

Prevalence of HER2-ultralow breast cancer in South Korea: a multicenter study by reassessment of HER2-zero cases

10.4132/jptm.2025.10.22 · 2026 · External reference

HER2-low and ultralow breast cancer: interobserver challenges and lessons from a consensus study

10.4132/jptm.2026.01.08 · 2026 · External reference

Current status and challenges in HER2 IHC assessment: scoring survey results in Japan

10.1007/s10549-024-07532-2 · 2025 · External reference

Standardizing the pathologic assessment of HER2-(ultra)low breast cancer: insights from a national Italian project

10.32074/1591-951x-1565 · 2025 · External reference

Clinicopathologic features and genomic profile of human epidermal growth factor receptor 2-low and human epidermal growth factor receptor 2-ultralow invasive breast carcinomas

10.5858/arpa.2025-0074-oa · 2025 · External reference

A bottom-up initiated digital external quality assessment scheme for the state-of-the-art pathology in Sweden: reduced variability between pathology departments

10.1007/s00428-025-04059-9 · 2026 · External reference

Global study on the accuracy of human epidermal growth factor receptor 2-low diagnosis in breast cancer

10.5858/arpa.2024-0052-oa · 2025 · External reference

HER2 immunohistochemistry interobserver reproducibility in 205 cases of invasive breast carcinoma additionally tested by ISH

10.1016/j.anndiagpath.2019.151451 · 2020 · External reference

Discerning subsets of breast cancer with very low and absent HER2 protein expression

10.1016/j.humpath.2022.05.019 · 2022 · External reference

Interobserver variability in HER-2 immunostaining interpretation of metastatic HER2 low breast cancers in cytology specimens

10.1002/dc.25392 · 2024 · External reference

HER2 testing by immunohistochemistry in breast cancer: a multicenter proficiency ring study

10.4103/ijpm.ijpm_983_20 · 2021 · External reference

Concordance in judgments among c-erbB-2 (HER2/neu) overexpression detected by two immunohistochemical tests and gene amplification detected by Southern blot hybridization in breast carcinoma

10.1046/j.1440-1827.2001.01163.x · 2001 · External reference

Evaluation of interobserver agreement in scoring immunohistochemical results of HER-2/neu (c-erbB-2) expression detected by HercepTest, Nichirei polyclonal antibody, CB11 and TAB250 in breast carcinoma

10.1046/j.1440-1827.2002.01327.x · 2002 · External reference

Interobserver reproducibility of immunohistochemical HER-2/neu evaluation in human breast cancer: the real-world experience

10.1177/172460080401900210 · 2004 · External reference

Interobserver reproducibility of immunohistochemical HER-2/neu assessment in human breast cancer: an update from INQAT round III

10.1177/172460080502000307 · 2005 · External reference

HER-2/neu gene amplification compared with HER-2/neu protein overexpression and interobserver reproducibility in invasive breast carcinoma

10.1309/vacp-vlqa-g9dx-vudf · 2000 · External reference

Interobserver reproducibility of Her-2/neu protein overexpression in invasive breast carcinoma using the DAKO HercepTest

10.1309/6anb-qxcf-ehkc-7uc7 · 2002 · External reference

Refining the definition of HER2-low class in invasive breast cancer

10.1111/his.14780 · 2022 · External reference

HER2 testing in multiple solid tumor types: concordance of immunohistochemistry scores between three HER2 scoring algorithms

10.1007/s00428-026-04398-1 · 2026 · External reference

Assessment of Ki67 in breast cancer: updated recommendations from the International Ki67 in Breast Cancer Working Group

10.1093/jnci/djaa201 · 2021 · External reference