Prognosis and endocrine therapy efficacy in early breast cancer with estrogen receptor low expression

In a retrospective cohort study of 2,951 patients with early-stage breast cancer, investigators evaluated the efficacy of endocrine therapy in patients with ER-low breast cancer. They found that HER2- ER-low breast cancer behaves similarly to triple-negative disease, and endocrine therapy can meaningfully lower recurrence and metastasis risk in this group; however, in HER2+ ER-low disease, there was no clear benefit from endocrine therapy.