Breast cancer index in premenopausal women with early-stage hormone receptor–positive breast cancer

In a prospective-retrospective translational analysis of the SOFT trial, the Breast Cancer Index (BCI) was shown to be prognostic in premenopausal women with HR+ breast cancer, with higher BCI continuous scores associated with worse outcomes. Patients with BCI HOXB13/IL17BR ratio–low tumors had greater benefit from ovarian function suppression–based adjuvant endocrine therapy than patients with BCI HOXB13/IL17BR ratio–high tumors.