The Impact of the HER2 Status(HER2 Low vs HER2 Negative) on the Pathological Response to Neoadjuvant Chemotherapy in Hormonal Receptor Positive Breast Cancer

Abstract Background More than 50% of breast cancers are currently defined as “Human epidermal growth factor receptor 2 (HER2) low breast cancer (BC)”. Nevertheless, little is known about the response and prognosis of HER2-low BC receiving neoadjuvant chemotherapy (NACT). Aim of the Work The purpose of our study is to evaluate the impact of HER2status (HER2 low vs zero) on the response to neoadjuvant chemotherapy (NACT) in HER2− BC. Patients and Methods This study is a retrospective study that included 96 patients attending the breast clinic at the Clinical Oncology Department, Ain Shams University during the period from 1 January 2020 till 31 December 2022. Results A total of 96 patients were included, of whom 68.8% were HER2 0, where HER2 low was represented by 31.2 % of the patients. HER2 low had similar pCR rates in comparison to HER2 0 (13.3% vs 18.2%, P = 0.55). Ki67 is highly significant correlated with pCR, as in patients who achieved pCR, Ki67 percent was of median 35%, while Ki67 was of median 20% in patients who didn’t achieve pCR (P < 0.01). Conclusion HER2-low status appears to be associated with a similar pCR rate as HER2-0 in HR positive BC patients.