Clinicopathologic Characteristics of Her2-low Breast Cancer in Egypt

Background: The emergence of Human epidermal growth factor receptor 2-Low (HER2-low) breast cancer as a distinct therapeutic category requires detailed characterization, particularly in understudied populations with unique clinical profiles, like Egypt.Aim of this study: To determine the clinicopathological characteristics of HER2-Low breast cancer patients in Egypt.Materials and Methods: A retrospective observational study was conducted on 309 invasive breast cancer patients classified as: HER2-Low (Immunohistochemistry 1+ or 2+/ In situ hybridization -; n=125) or HER2-zero (Immunohistochemistry (IHC) 0; n=184). Comprehensive data on demographics, presentation, pathology, treatment patterns, and survival were analysed using appropriate statistical methods. Results: Both groups showed similar demographic characteristics with median age of 50 years. Clinicopathological features were largely comparable, though HER2-Low tumors showed significantly less extranodal extension (56.7% vs 87.5%, p=0.002) and numerically higher hormone receptor positivity (84.8% vs 77.7%, p=0.284). Treatment patterns and metastatic distribution were similar between groups. Survival analysis revealed no significant differences in median overall survival (59 vs 60 months, p=0.773), disease-free survival, or progression-free survival.Conclusion/Recommendations: HER2-Low and HER2-zero breast cancers demonstrate remarkable clinicopathological similarity in Egyptian patients. The therapeutic relevance of HER2-low status appears more significant than its prognostic value. These findings highlight the critical need for standardized HER2 testing protocols to ensure accurate identification of patients eligible for novel treatments, particularly antibody-drug conjugate therapies.