Retrospective observational study of HER2 immunohistochemistry in borderline breast cancer patients undergoing neoadjuvant therapy, with an emphasis on Group 2 (HER2/CEP17 ratio ≥2.0, HER2 copy number <4.0 signals/cell) cases

  • Emad A. Rakha (Lead / Corresponding author)
  • , Islam M. Miligy
  • , Cecily M. Quinn
  • , Elena Provenzano
  • , Abeer M. Shaaban
  • , Caterina Marchiò
  • , Michael S. Toss
  • , Grace Gallagy
  • , Ciara Murray
  • , Janice Walshe
  • , Ayaka Katayama
  • , Karim Eldib
  • , Nahla Badr
  • , Bruce Tanchel
  • , Rebecca Millican-Slater
  • , Colin Purdie
  • , Dave Purnell
  • , Sarah E. Pinder
  • , Ian O. Ellis
  • , Andrew H. S. Lee

    Research output: Contribution to journalArticlepeer-review

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    Abstract

    Background: The ASCO/CAP guidance on HER2 testing in breast cancer (BC) has recently changed. Group 2 tumours with immunohistochemistry score 2+ and HER2/CEP17 ratio ≥2.0 and HER2 copy number <4.0 signals/cell were re-classified as HER2 negative. This study aims to examine the response of Group 2 tumours to neoadjuvant chemotherapy (NACT).

    Methods: 749 BC cases were identified from 11 institutions. The association between HER2 groups and pathological complete response (pCR) was assessed.

    Results: 54% of immunohistochemistry HER2 positive (score 3+) BCs showed pCR, compared to 19% of immunohistochemistry 2+ FISH amplified cases. 27% of Group 2 treated with HER2 targeted therapy achieved pCR, compared to 19 and 11% in the combined Groups 1 + 3 and Groups 4 + 5, respectively. No difference in pCR rates was identified between Group 2 and Group 1 or combined Groups 1 + 3. However, Group 2 response rate was higher than Groups 4 + 5 (p = 0.017).

    Conclusion: No difference in pCR was detected in tumours with a HER2/CEP17 ratio ≥2.0 and a HER2 score 2+ by IHC when stratified by HER2 gene copy number. Our data suggest that ASCO/CAP HER2 Group 2 carcinomas should be evaluated further with respect to eligibility for HER2 targeted therapy.

    Original languageEnglish
    Pages (from-to)1836-1842
    Number of pages7
    JournalBritish Journal of Cancer
    Volume124
    Early online date24 Mar 2021
    DOIs
    Publication statusPublished - 25 May 2021

    UN SDGs

    This output contributes to the following UN Sustainable Development Goals (SDGs)

    1. SDG 3 - Good Health and Well-being
      SDG 3 Good Health and Well-being

    Keywords

    • Breast cancer

    ASJC Scopus subject areas

    • Oncology
    • Cancer Research

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