Highlight
– BCI (H/I) remains a validated prognostic marker in premenopausal hormone receptor–positive breast cancer, with graded 12‑year distant recurrence risk across BCI-defined strata.
– In SOFT, BCI(H/I)-low tumors derived clear benefit from OFS-containing regimens relative to tamoxifen alone; in TEXT the BCI(H/I) status did not convincingly predict a larger advantage of exemestane+OFS over tamoxifen+OFS.
