HER2-positive breast cancer in patients with BRCA1/2 pathogenic variants: Case series and literature review

HER2-positive breast cancers are uncommonly reported in patients with BRCA1/2 pathogenic variants. The purpose of this case series is to describe three patients with BRCA1/2 pathogenic variants who developed HER2-positive breast cancers and their treatment courses along with that of a patient from a...

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Bibliographic Details
Published in:Current problems in cancer. Case reports 2025-03, Vol.17, p.100335, Article 100335
Main Authors: Munnangi, Pujita, Niravath, Polly Ann, Chang, Jenny C, Sun, Kai
Format: Article
Language:English
Subjects:
BRCA1
BRCA2
Breast cancer
Case report
Case series
HER2-positive
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Summary:HER2-positive breast cancers are uncommonly reported in patients with BRCA1/2 pathogenic variants. The purpose of this case series is to describe three patients with BRCA1/2 pathogenic variants who developed HER2-positive breast cancers and their treatment courses along with that of a patient from a previously published case report, and describe existing literature exploring associations between HER2-positive breast cancers and germline variants. HER2-positive breast cancer is uncommon in patients with BRCA1/2 pathogenic variants. The patients in our case series had hormone receptor positive and HER2-positive breast cancers. HER2 FISH was commonly utilized for the confirmation of HER2 status in our case series. All patients responded well to HER-2 directed therapies. While the interactions between BRCA1/2 pathogenic variants and the HER2 pathway are unclear, our case series and existing literature suggest that HER2-positive breast cancer occurrence is mainly HER2 oncogenic pathway driven. But the interplay between the DNA repair pathway and the HER2 oncogenic pathway could impact HER2 gene expression and play a potentially important role in treatment resistance and therapy options. Combining olaparib and trastuzumab could be considered for off-label use in patients with BRCA 1/2 mutations with HER2-positive breast cancer who failed HER2-targeted therapy. This study is limited by small sample size (n = 4). Since it is a retrospective study, it is also limited by selection bias, lack of control group for comparison purposes, and potential influence of confounding variables.
ISSN:2666-6219
2666-6219
DOI:10.1016/j.cpccr.2024.100335