Clinicopathological Characterization of HER2-Low-Expressing Triple-Negative Breast Cancer: Distinct Features From HER2-Zero Subtype.

HER2-low and HER2-zero triple-negative breast cancer are biologically distinct subgroups.

HER2-low tumors are enriched in luminal androgen receptor-like characteristics, whereas HER2-zero tumors exhibit basal-like, highly proliferative, and immunogenic features.

Although the treatment outcomes did not differ significantly, these findings suggest that HER2-low and HER2-zero triple-negative breast cancer may require different therapeutic approaches.

Prospective studies are warranted to validate these findings and further explore tailored treatment strategies.