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Breast Cancer With a HER2 FISH Group 2 Result: Should HER2 Tests be Repeated?
- Source :
-
Clinical breast cancer [Clin Breast Cancer] 2023 Jun; Vol. 23 (4), pp. 415-422. Date of Electronic Publication: 2023 Feb 12. - Publication Year :
- 2023
-
Abstract
- Background: Breast cancer with fluorescence in situ hybridization (FISH) group 2 pattern (HER2 <4 and HER2/CEP17 ratio ≥2, a subset of monosomy CEP17) was historically considered HER2-positive, but mostly HER2-negative according to updated 2018 American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines unless 3+ by immunohistochemistry (IHC). Therapeutic relevance of this group remained elusive, therefore we assessed if repeat IHC and FISH can assist final HER2 classification.<br />Patient and Methods: We retrospectively reviewed HER2 FISH performed at our institution from 2014 to 2018 and identified 23 of 3554 (0.6%) breast cancer cases with at least one-time measurement of HER2 FISH categorized as group 2. Repeat HER2 tests were performed for cases with available alternative tumor samples and compared with initial testing following 2018 ASCO/CAP guidelines.<br />Results: Only 1 of 23 group 2 cases was HER2-positive, 0/18 in primary and 1/5 in metastatic/recurrent tumors. Of 13 primary tumors with repeat HER2 results; 10 (77%) remained HER2-negative; 3 (23%) changed from HER2-negative (group 2 and IHC 2+) to HER2-positive (group 1 and IHC 2+). Among 8 of these 13 patients receiving neoadjuvant systemic therapy containing anti-HER2 agent, 3 (38%) achieved pathologic complete response (pCR). Two of 3 pCR cases were HER2-positive converters on repeat testing. Three pCR cases were ER-negative or -low positive and Ki67 ≥40%, while 5 partial responders were ER-positive and Ki67 <40% (P < .05).<br />Conclusion: Breast cancer with HER2 FISH group 2 result may represent heterogeneous populations of tumor cells being originated de novo or preferentially selected secondary to therapy. Repeat HER2 tests on alternative samples may be considered to guide anti-HER2 therapy.<br />Competing Interests: Disclosure All authors declare they have no conflicts of interest.<br /> (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Subjects :
- Humans
Female
In Situ Hybridization, Fluorescence methods
Receptor, ErbB-2 genetics
Receptor, ErbB-2 analysis
Retrospective Studies
Ki-67 Antigen
Neoplasm Recurrence, Local genetics
Biomarkers, Tumor genetics
Biomarkers, Tumor analysis
Breast Neoplasms genetics
Breast Neoplasms therapy
Breast Neoplasms pathology
Subjects
Details
- Language :
- English
- ISSN :
- 1938-0666
- Volume :
- 23
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Clinical breast cancer
- Publication Type :
- Academic Journal
- Accession number :
- 36878823
- Full Text :
- https://doi.org/10.1016/j.clbc.2023.02.006