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

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Abstract

Research purpose: 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. Key findings: 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. Conclusions & clinical implications: 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. Limitations: 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.

Original languageEnglish (US)
Article number100335
JournalCurrent Problems in Cancer: Case Reports
Volume17
DOIs
StatePublished - Mar 2025

Keywords

  • BRCA1
  • BRCA2
  • Breast cancer
  • Case report
  • Case series
  • HER2-positive

ASJC Scopus subject areas

  • Oncology

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