Neoadjuvant chemotherapy efficacy and prognosis in HER2-low and HER2-zero breast cancer patients by HR status: a retrospective study in China

• Published in: PeerJ (San Francisco, CA) Vol. 12; p. e17492
• Main Authors: Zhao, Shaorong, Wang, Yuyun, Zhou, Angxiao, Liu, Xu, Zhang, Yi, Zhang, Jin
• Format: Journal Article
• Language: English
• Published: United States PeerJ Inc 2024
• Subjects: Adult; Aged; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - genetics; Breast Neoplasms - mortality; Breast Neoplasms - pathology; Chemotherapy, Adjuvant; China - epidemiology; Disease-free survival; Female; Human epidermal growth factor receptor 2; Humans; Middle Aged; Neoadjuvant chemotherapy; Neoadjuvant Therapy - methods; Pathological complete response; Prognosis; Receptor, ErbB-2 - genetics; Receptor, ErbB-2 - metabolism; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Retrospective Studies; Treatment Outcome; China; Neoadjuvant chemotherapy; Pathological complete response; Breast cancer; Human epidermal growth factor receptor 2; Disease-free survival
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.17492

The promising efficacy of novel anti-HER2 antibody-drug conjugates (ADC) in HER2-low breast cancer has made HER2-low a research hotspot. However, controversy remains regarding the neoadjuvant chemotherapy (NAC) efficacy, prognosis, and the relationship with hormone receptor (HR) status of HER2-low. A retrospective analysis was conducted on 975 patients with HER2-negative breast cancer undergoing NAC at Tianjin Medical University Cancer Institute and Hospital, evaluating pathological complete response (pCR) rate and prognosis between HER2-low and HER2-zero in the overall cohort and subgroups. Overall, 579 (59.4%) and 396 (40.6%) patients were HER2-low and HER2-zero disease, respectively. Compared with HER2-zero, the HER2-low cohort consists of more postmenopausal patients, with lower histological grade and higher HR positivity. In the HR-positive subgroup, HER2-low cases remain to exhibit lower histological grade, while in the HR-negative subgroup, they show higher grade. The HER2-low group had lower pCR rates than the HER2-zero group (16.4% . 24.0%). In the HR-positive subgroup, HER2-low consistently showed lower pCR rate (8.1% . 15.5%), and served as an independent suppressive factor for the pCR rate. However, no significant difference was observed in the pCR rates between HER2-low and HER2-zero in the HR-negative breast cancer. In the entire cohort and in stratified subgroups based on HR and pCR statuses, no difference in disease-free survival were observed between HER2-low and HER2-zero. In the Chinese population, HER2-low breast cancer exhibits distinct characteristics and efficacy of NAC in different HR subgroups. Its reduced pCR rate in HR-positive subgroup is particularly important for clinical decisions. However, HER2-low is not a reliable factor for assessing long-term survival outcomes.