Influence of HER2 Expression on Prognosis in Metastatic Triple-Negative Breast Cancer—Results From an International, Multicenter Analysis Coordinated by the AGMT Study Group

An international, multicenter analysis including 691 patients with metastatic triple-negative breast cancer found that the frequency of HER2-low was 32.0%. Similar frequencies were seen in metastases (29.8%) and primary tumors (33.4%; P = 0.324). There was no statistically different overall survival between HER2-low and HER2-0 TNBC (HR 1.00; P = 0.969), and there was no significant impact of HER2-low on overall survival in multivariable analysis (HR 0.95; P = 0.545).