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The differences of clinicopathologic characteristics among subgroups of reclassified HER2 fluorescence in situ hybridization (FISH) according to the ASCO/CAP 2018 breast cancer HER2 testing guidelines
  1. Libo Yang1,2,
  2. Min Chen1,
  3. Tianjie Pu1,2,
  4. Shuang Wu1,
  5. Bing Wei1,
  6. Jieliang Yang1,
  7. Hong Bu1,2,
  8. Zhang Zhang1
  1. 1Department of Pathology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
  2. 2Laboratory of Pathology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
  1. Correspondence to Dr Zhang Zhang, Department of Pathology, West China Hospital of Sichuan University, Chengdu, Sichuan, China; zhangzhang714{at}163.com

Abstract

Aims The aim of this study is to analyse differences in clinicopathologic features among reclassified human epidermal growth factor receptor-2 (HER2) fluorescence in situ hybridization (FISH) results in breast cancers according to 2018 guidelines.

Methods According to different ratios of HER2 copy numbers to chromosome 17 centromere numbers (HER2/CEP17) and average HER2 copy numbers, 3795 invasive breast cancers were classified into six groups. Clinicopathologic features were collected and compared among different FISH groups.

Results There were no statistically significant differences about HER2 positive rate between 2013 and 2018 guidelines (p=0.518). After re-evaluating these cases according to 2018 guidelines, the cases that converted to a HER2 positive status had clinicopathologic features similar to samples in group 1 (ratio ≥2.0, HER2 ≥4.0). Compared with group 5 (ratio <2.0, HER2 <4.0), the cases in groups 1 had higher histological grade, more frequent occurrence of negative oestrogen receptor and progesterone receptor status and a higher Ki67 index. The samples in group 4 (ratio <2.0, 4.0≤HER2<6.0) showed a higher histological grade and higher Ki67 index than did the samples in group 5 but had a lower histological grade and lower Ki67 index than did the samples in group 1a (ratio ≥2.0, HER2 ≥6.0).

Conclusion Different categories of HER2 FISH test results have significant differences in clinicopathologic features. With no equivocal cases in 2018 HER2 guidelines, the clear division of HER2 status is helpful for making treatment recommendations about HER2 targeted therapy.

  • breast cancer
  • immunohistochemistry
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Footnotes

  • Handling editor Runjan Chetty.

  • LY and MC contributed equally.

  • Contributors ZZ and HB made contributions to the design of this study. LY, SW and MC collected data. ZZ, MC, LY, JY and TP reviewed slides. LY conducted statistical analyses and drafted the manuscript. ZZ and BW were involved in revising the manuscript.

  • Funding This research received grant from National Natural Science Foundation of China (Grant No. 81702599).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the institutional Ethics Committee of West China Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request.

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