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 RakhaIslam M MiligyCecily M QuinnElena ProvenzanoAbeer M ShaabanCaterina MarchiòMichael S TossGrace GallagyCiara MurrayJanice WalsheAyaka KatayamaKarim EldibNahla BadrBruce TanchelRebecca Millican-SlaterColin PurdieDave PurnellSarah E PinderIan O EllisAndrew H S LeePublished in: British journal of cancer (2021)
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.