1Department Of Clinical Oncology and Nuclear Medicine , Faculty of Medicine , Alexandria University
2Department of Clinical Oncology and Nuclear Medicine,‎ Faculty of Medicine,‎ Alexandria University.‎
3Department of Cancer Management and Research,‎ Medical Research Institute,‎ Alexandria University.‎
4Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Alexandria University
Abstract
Introduction
The recently highlighted HER2 low breast cancer (BC) subgroup (IHC 1+ or IHC 2+/ISH negative) has challenged the established binary categorization of BC into HER2 overexpressing tumors and HER2 negative. This raises the question of whether the HER2 low status influences disease phenotype in a manner similar to HER2 overexpression. Aim To Identify the prevalence of low HER-2 status among non-metastatic BC patients in comparison to HER-2 negative and HER-2 positive, and to compare treatment outcome of HER-2 low to HER-2 negative non-metastatic BC.
Patients and methods This retrospective study of 1029 early BC patients diagnosed between 2014 and 2022 in Alexandria university hospitals. Tumors originally reported as HER2 negative were recategorized into HER2 0 and HER2 low based on the results of IHC and FISH. HER2 low and HER2 positive groups were compared to HER2-0 in terms of clinical and pathological features. Results 192 (18.7%) patients were HER2 positive, 779 (75.7%) were reported as HER2 negative, and were reclassified into 441 (56%) HER2-0, and 338 (43%) HER2 low. 58 (5.6%) patients with undetermined HER2 status were excluded.