Exploring the clinicopathological parameters of HER2 low breast cancers: insights from a retrospective cohort study

Breast cancer subtypes are delineated by human epidermal growth factor receptor 2 (HER2) expression, pivotal in treatment selection. HER2-positive tumors typically respond to targeted therapies, whereas HER2-negative tumors lack HER2 overexpression. However, a subset exhibits low HER2 expression without amplification, termed HER2 low breast cancer. Despite being distinct, its clinicopathological characteristics and therapeutic implications remain less understood.

A retrospective cohort study was conducted on histologically confirmed breast cancer cases from January 2022 to December 2023. Clinicopathological data including age, tumor size, nodal involvement, and hormone receptor status were collected. Immunohistochemistry categorized tumors into luminal, triple-negative, and HER2-enriched subtypes. HER2 expression was re-evaluated, classifying tumors into HER2 low and HER2-negative based on staining intensity and amplification status. Statistical analysis was performed using SPSS software.

Seventy female patients with breast cancer were included, exhibiting diverse clinicopathological features. HER2 low tumors (40%) were significantly associated with higher tumor stage (P=0.03), nodal involvement (P=0.01), and positive androgen receptor expression (P=0.01). Subgroup analysis revealed HER2 low hormone receptor-positive cases (78.6%) were associated with higher tumor stage (P=0.01) and nodal involvement (P=0.01), while HER2 low triple-negative cases (21.4%) demonstrated distinct characteristics such as higher histological grade (P=0.02).

This study underscores the complexity of HER2 low breast cancer and its implications for clinical management, emphasizing the need for personalized treatment strategies. It provides insights into the clinicopathological parameters of HER2 low breast cancers, highlighting their diverse characteristics and clinical implications.