Should a borderline negative HER2 result in a core biopsy of invasive carcinoma of the breast have HER2 assessment repeated in the excision specimen?
Lee, Andrew H S Hodi, Zsolt Abbas, Areeg Wencyk, Peter Ellis, Ian O Rakha, Emad
Lee, Andrew H S
Hodi, Zsolt
Abbas, Areeg
Wencyk, Peter
Ellis, Ian O
Rakha, Emad
Abstract
AIM: The 2015 UK guidelines for HER2 assessment in breast cancer recommended repeat assessment if the core biopsy was scored as 2+ on HER2 immunohistochemistry (IHC) with borderline negative in situ hybridisation (ratio of number of HER2 to chromosome 17 centromere copies of 1.8-1.99). This case series aimed to assess the value of such repeat assessment in the surgical specimen, in particular the proportion that were HER2 positive.
METHODS: Details of biopsies with 2+ IHC and borderline negative in situ hybridisation were extracted from a database. The results of repeat HER2 testing in the surgical specimen for this cohort study were then obtained.
RESULTS: 112 patients with no preoperative treatment had repeat assessment: 4 were 3+ and 16 were 2+ amplified. Of 14 with preoperative chemotherapy, 1 was 3+ and 4 were 2+ amplified. All the 2+ amplified carcinomas had a HER2 to chromosome 17 ratio less than 4, in 50% the ratio was between 2.0 and 2.2, and in 50% the HER2 copy number was less than 4.
CONCLUSIONS: Repeat assessment yielded 4% 3+ results and 14% 2+ amplified carcinomas but with low level amplification. These results suggest that retesting of borderline negative HER2 cases should be optional and no longer mandatory.
MIDER Authors
Lee, Andrew H S
Hodi, Zsolt
Abbas, Areeg
Ellis, Ian O
Rakha, Emad
Hodi, Zsolt
Abbas, Areeg
Ellis, Ian O
Rakha, Emad
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Date
2024-10-20
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Article
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Citation
Lee A.H.S., Hodi Z., Abbas A., Wencyk P., Ellis I.O. and Rakha E. (2024) 'Should a borderline negative HER2 result in a core biopsy of invasive carcinoma of the breast have HER2 assessment repeated in the excision specimen?', Journal of clinical pathology, 77(11), pp. 726 EP. doi: 10.1136/jcp-2023-209091 https://doi.org/10.1136/jcp-2023-209091.