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Palm C, Connolly CE, Masser R, Padberg Sgier B, Karamitopoulou E, Simon Q, Bode B, Tinguely M. Determining HER2 Status by Artificial Intelligence: An Investigation of Primary, Metastatic, and HER2 Low Breast Tumors. Diagnostics (Basel) 2023; 13:diagnostics13010168. [PMID: 36611460 PMCID: PMC9818571 DOI: 10.3390/diagnostics13010168] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/21/2022] [Accepted: 12/24/2022] [Indexed: 01/05/2023] Open
Abstract
The expression of human epidermal growth factor receptor 2 (HER2) protein or gene transcripts is critical for therapeutic decision making in breast cancer. We examined the performance of a digitalized and artificial intelligence (AI)-assisted workflow for HER2 status determination in accordance with the American Society of Clinical Oncology (ASCO)/College of Pathologists (CAP) guidelines. Our preliminary cohort consisted of 495 primary breast carcinomas, and our study cohort included 67 primary breast carcinomas and 30 metastatic deposits, which were evaluated for HER2 status by immunohistochemistry (IHC) and in situ hybridization (ISH). Three practicing breast pathologists independently assessed and scored slides, building the ground truth. Following a washout period, pathologists were provided with the results of the AI digital image analysis (DIA) and asked to reassess the slides. Both rounds of assessment from the pathologists were compared to the AI results and ground truth for each slide. We observed an overall HER2 positivity rate of 15% in our study cohort. Moderate agreement (Cohen's κ 0.59) was observed between the ground truth and AI on IHC, with most discrepancies occurring between 0 and 1+ scores. Inter-observer agreement amongst pathologists was substantial (Fleiss´ κ 0.77) and pathologists' agreement with AI scores was 80.6%. Substantial agreement of the AI with the ground truth (Cohen´s κ 0.80) was detected on ISH-stained slides, and the accuracy of AI was similar for the primary and metastatic tumors. We demonstrated the feasibility of a combined HER2 IHC and ISH AI workflow, with a Cohen's κ of 0.94 when assessed in accordance with the ASCO/CAP recommendations.
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Affiliation(s)
- Christiane Palm
- Pathologie Institute Enge, 8005 Zurich, Switzerland
- Faculty of Medicine, University of Zurich, 8006 Zurich, Switzerland
| | | | | | | | | | | | - Beata Bode
- Pathologie Institute Enge, 8005 Zurich, Switzerland
- Faculty of Medicine, University of Zurich, 8006 Zurich, Switzerland
| | - Marianne Tinguely
- Pathologie Institute Enge, 8005 Zurich, Switzerland
- Faculty of Medicine, University of Zurich, 8006 Zurich, Switzerland
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Md Pauzi SH, Masir N, Yahaya A, Mohammed F, Tizen Laim NMS, Mustangin M, Aizudin AN, Talib A, Teoh KH, Karim N, Oy-Leng JW, Rajadurai P. HER2 testing by immunohistochemistry in breast cancer: A multicenter proficiency ring study. INDIAN J PATHOL MICR 2021; 64:677-682. [PMID: 34673585 DOI: 10.4103/ijpm.ijpm_983_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background Human epidermal growth factor receptor 2 (HER2) over-expression in breast cancer is associated with aggressive tumor behavior and predicts response to targeted therapy. Accurate HER2 result is paramount for optimal patient management. However, routine HER2 immunohistochemistry (IHC) testing are subjected to intra- and inter-laboratory variability. Objective This study aims to determine inter-laboratory variation in HER2 IHC testing through a slide-exchange program between five main reference laboratories. Method A total of 20 breast carcinoma cases with different known HER2 expression and gene status were selected by the central laboratory in five testing rounds. Three unstained tissue sections from each case were sent to participating laboratories, which immunostained and interpreted the HER2 immunohistochemistry result. One of the stained slides was sent to one designated participating laboratory for evaluation. Results were analyzed by the central laboratory. Results A complete concordance was achieved in six IHC-positive and six IHC-negative cases, its gene status of which was confirmed by in-situ-hybridization (ISH) study. The discordant results were observed in six equivocal cases, one negative case and one positive case with a concordance rate of 50-88.3%. Interestingly, the negative discordant case actually displays tumor heterogeneity. Good inter-observer agreement was achieved for all participating laboratories (k = 0.713-1.0). Conclusion Standardization of HER2 testing method is important to achieve optimum inter-laboratory concordance. Discordant results were seen mainly in equivocal cases. Intra-tumoral heterogeneity may impact the final HER2 IHC scoring. The continuous quality evaluation is therefore paramount to achieve reliable HER2 results.
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Affiliation(s)
- Suria Hayati Md Pauzi
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Noraidah Masir
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Azyani Yahaya
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Fazarina Mohammed
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Nur Maya Sabrina Tizen Laim
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Muatamarulain Mustangin
- Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Azimatun Noor Aizudin
- Department of Community Health, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Arni Talib
- Department of Pathology, Hospital Kuala Lumpur, Kuala Lumpur, Malaysia
| | - Kean-Hooi Teoh
- Department of Pathology, University Malaya Medical Centre, Lembah Pantai, Kuala Lumpur, Kuala Lumpur
| | - Norain Karim
- Department of Pathology, Hospital Raja Permaisuri Bainun, 30450 Ipoh, Perak, Malaysia
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Taylor VJ, Barnes PJ, Godwin SC, Bethune GC. Assessment of HER2 using the 2018 ASCO/CAP guideline update for invasive breast cancer: a critical look at cases classified as HER2 2+ by immunohistochemistry. Virchows Arch 2021; 479:23-31. [PMID: 33527151 DOI: 10.1007/s00428-021-03034-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/08/2021] [Accepted: 01/13/2021] [Indexed: 12/14/2022]
Abstract
In 2018, the American Society of Clinical Oncology/College of American Pathologists revised the criteria for HER2 immunohistochemistry (IHC) equivocal (2+) classification in their updated guideline. We reviewed invasive breast cancer specimens originally classified as equivocal (2+) under the 2018 guideline that underwent HER2 fluorescence in situ hybridization (FISH) testing from August 2018 to August 2019 at our Canadian reference hospital to investigate cases with ambiguous staining patterns between the 1+ and 2+ definitions. Demographics, pathologic features, and pre-analytic conditions were recorded. The H&E and corresponding HER2 IHC slides were reviewed to confirm tumor type and grade, and classify as HER2 indeterminate, 0, 1+, 2+, or "Intermediate" (staining features between the 1+ and 2+ classifications). FISH testing was performed on 289 cases and 273 met inclusion criteria. The FISH-amplified rate was 12.1%. Upon IHC review, 44.7% (122/273) of cases were reclassified as Intermediate. These cases had incomplete staining with moderate intensity (43/122, 35.3%) and/or <10% complete weak or moderate staining (102/122, 83.6%). Intermediate cases had a significantly lower frequency of amplified FISH results than 2+ cases (p < 0.0001), with only four (3.3%) FISH positive and two (1.6%) FISH heterogeneous. Our study highlights the ambiguity in the current guideline for classifying some HER2 IHC patterns. As the rate of gene amplification in these cases was low (4.9%), we recommend adhering to the 2018 HER2 2+ criteria for reflex FISH testing. However, cases with <10% moderate complete staining and certain heterogeneous patterns warrant special consideration. Further descriptive clarification of 1+ criteria is needed.
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Chatzopoulos K, Collins AR, Sotiriou S, Keeney MG, Visscher DW, Rivera M, Schembri-Wismayer DJ, Lewis JE, Greipp PT, Sukov WR, Chintakuntlawar AV, Price KA, Garcia JJ. Increased ERBB2 Gene Copy Numbers Reveal a Subset of Salivary Duct Carcinomas with High Densities of Tumor Infiltrating Lymphocytes and PD-L1 Expression. Head Neck Pathol 2020; 14:951-965. [PMID: 32350809 PMCID: PMC7669929 DOI: 10.1007/s12105-020-01163-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/22/2020] [Indexed: 02/08/2023]
Abstract
Salivary duct carcinoma (SDC) commonly expresses androgen receptor (AR) and HER2, giving rise to treatment implications. SDC may also express programmed-death-ligand-1 (PD-L1), a predictive marker of response to checkpoint inhibitors. PD-L1 can be associated with genomic instability and high density of tumor infiltrating lymphocytes (TILs). Evaluation of HER2 immunohistochemistry (IHC) in SDC is not standardized, and relationships between ERBB2 copy numbers, PD-L1 expression and TILs in SDC are unknown. We evaluated 32 SDCs for HER2, AR and PD-L1 expression (IHC), ERBB2 status (FISH) and TILs (slide review). HER2 was scored with three different systems (breast, gastric, proposed salivary gland). PD-L1 was evaluated with the combined positive score. Most patients were older men, presenting at advanced clinical stage with nodal or distant metastases. During follow-up (mean 5 years, range 6 months to 21 years), 25 of the 32 patients (78%) died of SDC. We propose a HER2 IHC scoring system which accurately predicts underlying ERBB2 amplification or increased copy numbers in SDC. Most tumors had increased ERBB2 copy numbers (19/32 amplification, 6/32 aneusomy), a finding associated with higher TIL densities (p = 0.045) and PD-L1 expression (p = 0.025). Patients with TILs ≥ 40% had better prognoses (Log-Rank p = 0.013), with TILs being favorable prognosticators in univariate analysis (Hazard ratio: 0.18, p = 0.024). A subset of SDCs with increased ERBB2 copy numbers have higher TILs and PD-L1 expression. TILs ≥ 40% are associated with better prognosis.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- B7-H1 Antigen/biosynthesis
- Biomarkers, Tumor/analysis
- Carcinoma, Ductal/genetics
- Carcinoma, Ductal/immunology
- Carcinoma, Ductal/pathology
- DNA Copy Number Variations
- Female
- Gene Amplification
- Genes, erbB-2
- Humans
- Lymphocytes, Tumor-Infiltrating/immunology
- Lymphocytes, Tumor-Infiltrating/pathology
- Male
- Middle Aged
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Salivary Gland Neoplasms/genetics
- Salivary Gland Neoplasms/immunology
- Salivary Gland Neoplasms/pathology
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Affiliation(s)
| | | | - Sotiris Sotiriou
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - Michael G. Keeney
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - Daniel W. Visscher
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - Michael Rivera
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | | | - Jean E. Lewis
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - Patricia T. Greipp
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | - William R. Sukov
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
| | | | | | - Joaquin J. Garcia
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN USA
- Division of Anatomic Pathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 USA
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Li AC, Zhao J, Zhao C, Ma Z, Hartage R, Zhang Y, Li X, Parwani AV. Quantitative digital imaging analysis of HER2 immunohistochemistry predicts the response to anti-HER2 neoadjuvant chemotherapy in HER2-positive breast carcinoma. Breast Cancer Res Treat 2020; 180:321-329. [PMID: 32002765 DOI: 10.1007/s10549-020-05546-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 01/21/2020] [Indexed: 01/04/2023]
Abstract
PURPOSE Patients with HER2-positive breast cancer commonly receive anti-HER2 neoadjuvant chemotherapy and pathologic complete response (pCR) can be achieved in up to half of the patients. HER2 protein expression detected by immunohistochemistry (IHC) can be quantified using digital imaging analysis (DIA) as a value of membranous connectivity. We aimed to investigate the association HER2 IHC DIA quantitative results with response to anti-HER2 neoadjuvant chemotherapy. METHODS Digitized HER2 IHC whole slide images were analyzed using Visiopharm HER2-CONNECT to obtain quantitative HER2 membranous connectivity from a cohort of 153 HER2+ invasive breast carcinoma cases treated with anti-HER2 neoadjuvant chemotherapy (NAC). HER2 connectivity and other factors including age, histologic grade, ER, PR, and HER2 fluorescence in situ hybridization (FISH) were analyzed for association with the response to anti-HER2 NAC. RESULTS Eighty-three cases (54.2%) had pCR, while 70 (45.8%) showed residual tumor. Younger age, negative ER/PR, higher HER2 DIA connectivity, higher HER2 FISH ratio and copy number were significantly associated with pCR in univariate analysis. Multivariate analysis demonstrated only age, HER2 DIA connectivity, PR negativity, and HER2 copy number was significantly associated with pCR, whereas HER2 DIA connectivity had the strongest association. CONCLUSIONS HER2 IHC DIA connectivity is the most important factor predicting pCR to anti-HER2 neoadjuvant chemotherapy in patients with HER2-positive breast cancer.
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Affiliation(s)
- Aidan C Li
- Dublin Jerome High School, Dublin, OH, USA
| | - Jing Zhao
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Chao Zhao
- Center for Biostatistics, Emory University, Atlanta, GA, USA
| | - Zhongliang Ma
- Department of Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Ramon Hartage
- Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Yunxiang Zhang
- Department of Pathology, Weifang People's Hospital, Weifang, China
| | - Xiaoxian Li
- Department of Pathology, Emory University, Atlanta, GA, USA.
| | - Anil V Parwani
- Department of Pathology, The Ohio State University, Columbus, OH, USA.
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Ko YS, Kim NY, Pyo JS. Concordance analysis between HER2 immunohistochemistry and in situ hybridization in non-small cell lung cancer. Int J Biol Markers 2018; 33:49-54. [PMID: 28478639 DOI: 10.5301/ijbm.5000271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE This study aimed to elucidate the concordance between human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) and in situ hybridization (ISH) and the diagnostic accuracy of HER2 IHC in non-small cell lung cancer (NSCLC) through a meta-analysis and diagnostic test accuracy review. METHODS Seven eligible studies and 1,217 patients with NSCLC were included in the review. The concordance between HER2 IHC and ISH was analyzed. To confirm the diagnostic accuracy of HER2 IHC, the sensitivity and specificity were analyzed and the area under the curve (AUC) in the summary receiver operating characteristic (SROC) curve was calculated. RESULTS The concordance rate between HER2 IHC and ISH was 0.795 (95% confidence interval [CI] 0.534-0.929). In the HER2 IHC-negative (score 0/1+) subgroup, the concordance rate was 0.975 (95% CI 0.854-0.996). The concordance rates of the HER2 IHC score 2+ and 3+ subgroups were 0.091 (95% CI 0.039-0.197) and 0.665 (95% CI 0.446-0.830), respectively. In diagnostic test accuracy review, the pooled sensitivity and specificity were 0.67 (95% CI 0.54-0.78) and 0.89 (95% CI 0.87-0.91), respectively. The AUC in the SROC curve was 0.891 and the diagnostic odds ratio was 16.99 (95% CI 5.08-56.76). CONCLUSIONS HER2 IHC was largely in agreement with ISH in cases of HER2 IHC score 0/1+. Because the concordance rates of HER2 IHC score 2/3+ cases were lower than that of HER2 IHC score 0/1+ cases, further studies for detailed analysis criteria for HER2 IHC score 2+ or 3+ are required.
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Tchrakian N, Flanagan L, Harford J, Gannon JM, Quinn CM. New ASCO/CAP guideline recommendations for HER2 testing increase the proportion of reflex in situ hybridization tests and of HER2 positive breast cancers. Virchows Arch 2015; 468:207-11. [PMID: 26521061 DOI: 10.1007/s00428-015-1871-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 10/03/2015] [Accepted: 10/21/2015] [Indexed: 11/26/2022]
Abstract
Accurate determination of tumour human epidermal growth factor receptor type 2 (HER2) status is critical for optimal treatment of breast cancer. In October 2013, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) issued joint updated guideline recommendations for HER2 testing in breast cancer, with a revised algorithm for interpretation of immunohistochemistry (IHC) and in situ hybridisation (ISH) results. This study investigates the impact on HER2 IHC categorisation, implication for reflex ISH testing and potential for identification of false negative IHC. HER2 IHC preparations on 251 invasive breast tumours, originally reported according to 2007 guidelines, were re-scored using 2013 guidelines and the diagnostic categories compared. The results of ISH testing on a separate cohort of 32 breast tumours reported as HER2 IHC 2+ following the introduction of the 2013 guidelines, that would have been designated 1+ according to 2007, were reviewed. Application of 2013 guidelines resulted in a decrease in tumours classified as HER2 negative (83/251 vs 144/251) and a comparable increase in those classified as equivocal (2+) (139/251 vs 80/251). Relatively few tumours were re-classified as positive (29/251 vs 27/251). Furthermore, 3/32 breast cancer cases (HER2 IHC 2+ as per 2013 guidelines, 1+ using 2007 guidelines) were HER2 ISH positive. Application of the 2013 guidelines increases the HER2 IHC equivocal (2+) category and requirement for reflex ISH testing. The reduced threshold for ISH testing identifies some patients with HER2 positive breast cancer whose tumours would have been categorised as HER2 negative according to the 2007 guidelines.
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Affiliation(s)
- N Tchrakian
- Department of Histopathology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
| | - L Flanagan
- Department of Histopathology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
| | - J Harford
- Department of Histopathology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
| | - J M Gannon
- University College Dublin, Dublin 4, Ireland.
| | - C M Quinn
- Department of Histopathology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
- University College Dublin, Dublin 4, Ireland.
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Li Z, Dabbs DJ, Cooper KL, Bhargava R. Dual HER2 gene protein assay: focused study of breast cancers with 2+ immunohistochemical expression. Am J Clin Pathol 2015; 143:451-8. [PMID: 25696805 DOI: 10.1309/ajcpkivvw4obpx6i] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
OBJECTIVES The combined gene protein assay (GPA) can simultaneously assess HER2 gene copy number and protein on a single slide using bright-field microscopy. METHODS GPA was compared with a fluorescence in situ hybridization (FISH) assay on 50 invasive breast carcinomas with a 2+ score on immunohistochemistry (IHC). RESULTS The cases were categorized into positive, equivocal, or negative for HER2 gene amplification using the 2013 American Society of Clinical Oncology/College of American Pathologists criteria. This resulted in 82% agreement (41 of 50) between FISH and GPA. In addition, 25 known IHC 3+ breast carcinomas analyzed by GPA showed protein overexpression and clusters of HER2 gene consistent with unequivocal amplification, and 22 known IHC-negative cases were negative for HER2 gene amplification by GPA. CONCLUSIONS Although GPA is an alternative to both IHC and FISH, it may be an unnecessary test for IHC 0/1+/3+ cases. The clinical utility of GPA appears to be similar to other in situ hybridization assays (ie, adjudicator of HER2 status for IHC 2+ cases).
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Affiliation(s)
- Zaibo Li
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
| | - David J. Dabbs
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Kristine L. Cooper
- University of Pittsburgh Cancer Institute Biostatistics Facility, Pittsburgh, PA
| | - Rohit Bhargava
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
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Gao FF, Dabbs DJ, Cooper KL, Bhargava R. Bright-field HER2 dual in situ hybridization (DISH) assay vs fluorescence in situ hybridization (FISH): focused study of immunohistochemical 2+ cases. Am J Clin Pathol 2014; 141:102-10. [PMID: 24343743 DOI: 10.1309/ajcp6cxs8osrhxir] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES To compare the INFORM HER2 bright-field dual in situ hybridization (DISH) DNA probe cocktail assay with the PathVysion fluorescence in situ hybridization (FISH) assay on 103 invasive breast carcinomas with a 2+ score on immunohistochemistry (IHC). METHODS The cases were categorized as positive, equivocal, or negative for HER2 gene amplification using the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2:CEP17 ratio criteria and also based on mean HER2 gene copies/cell. The third criterion used a HER2:CEP17 ratio of 2 to categorize cases as positive or negative. RESULTS The agreement between FISH and DISH was 85% using the 2007 ASCO/CAP ratio criterion, 79% using the mean HER2 gene copies/cell criterion, and 92% using the 2.0 cutoff HER2:CEP17 ratio criterion. In addition, 20 known IHC 3+ breast carcinomas analyzed by DISH showed clusters of the HER2 gene consistent with unequivocal amplification. CONCLUSIONS Despite some technical and interpretational issues associated with DISH, it compares favorably with FISH in this group of challenging breast cancer cases.
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Affiliation(s)
- Faye F. Gao
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
| | - David J. Dabbs
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Kristine L. Cooper
- University of Pittsburgh Cancer Institute Biostatistics Facility, Pittsburgh, PA
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
| | - Rohit Bhargava
- Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA
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