Zhao J, Krishnamurti U, Zhang C, Meisel J, Wei Z, Suo A, Aneja R, Li Z, Li X. HER2 immunohistochemistry staining positivity is strongly predictive of tumor response to neoadjuvant chemotherapy in HER2 positive breast cancer.
Pathol Res Pract 2020;
216:153155. [PMID:
32871536 DOI:
10.1016/j.prp.2020.153155]
[Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/30/2020] [Accepted: 08/01/2020] [Indexed: 11/21/2022]
Abstract
BACKGROUND
The current recommendation is to reflex test HER2 immunohistochemistry (IHC) equivocal breast cancer cases with fluorescence in situ hybridization (FISH) analysis. Either IHC 3+ or FISH positive cancers are considered HER2 positive (HER2+) and treated with HER2 targeted therapy. This study examined the predictive value of HER IHC or FISH positivity in tumor response to HER2 targeted therapy.
METHODS
Biopsies of 76 HER2+ breast cancer cases were evaluated. All patients were treated with neoadjuvant HER2 targeted therapy and chemotherapy. Tumor response was evaluated on the excisional specimens. Cancers with complete pathologic response (pCR) or MD Anderson residual cancer burden-I (RCB-I) were classified as responders and cancers with RCB-II/III as non-responders. Clinicopathologic parameters were correlated with response.
RESULTS
In univariate analysis, small tumor size, low nuclear grade, high Ki67, HER2 IHC 3+, homogenous strong HER2 IHC staining, high HER2/CEP17 ratio, and high HER2 copy number were significantly associated with pCR/RCB-I. In multivariate analysis, homogenous strong HER2 IHC staining pattern was significantly associated with pCR/RCB-I. The receiver operating characteristics (ROC) model showed either high HER2/CEP17 ratio or HER2 copy number individually was predictive of tumor response.
CONCLUSION
HER2 IHC staining pattern is significantly associated with tumor response to neoadjuvant chemotherapy, reiterating the importance of HER2 IHC evaluation. The ROC model shows either high HER2/CEP17 ratio or high HER2 copy number individually is predictive of tumor response to neoadjuvant HER2 targeted therapy in HER2+ breast cancer.
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