Age

18–80

Sex

FEMALE

Healthy volunteers

Not accepted

Patients with advanced or locally unresectable breast cancer;
Treated with T-DXd (DS-8201, trastuzumab deruxtecan) regardless of line of therapy, HR, and HER2 expression level;
HER2 immunohistochemistry staining information of the primary lesion or metastatic/recurrent lesion;
Measurable lesions with treatment response results that can be evaluated through imaging examinations;
Able to follow up with the latest progression-free survival or overall survival.

Patients with missing basic clinical information or HER2 immunohistochemistry staining information;
Patients with missing pathological results for both primary and metastatic/recurrent lesions;
Patients with no measurable lesions and unable to evaluate T-DXd treatment response;
Discontinue T-DXd therapy for unacceptable adverse events or other reasons;
Patients lost to follow-up after T-DXd treatment.

Efficacy of Trastuzumab Deruxtecan in Metastatic Breast Cancer With Different HER2 Expression Patterns