BCI biomarker performance in premenopausal women with breast cancer.

Abstract

e12506 Background: Breast Cancer Index (BCI) is a gene expression biomarker that evaluates cell proliferation and estrogen signaling to guide extended endocrine therapy treatment in hormone receptor-positive breast cancer. BCI assay predicts the benefit of extended endocrine therapy and provides a prognostic score to assess both overall recurrence risk (0-10 years) and late distant recurrence risk (5-10 years). While the assay is validated in trials like MA-17, TEAM, IDEAL, aTTom and NSABP-B42, these studies focused on postmenopausal patients. The role of BCI in premenopausal women, with their unique hormonal and therapeutic profiles, remains underexplored. This retrospective, single-center study seeks to validate BCI in a premenopausal cohort. Methods: Premenopausal status was defined by self-reported last menstrual period or age <50 years. A total of 99 premenopausal patients with hormone receptor-positive breast cancer were included. Clinical and pathological data were collected, and BCI scores were evaluated for their prognostic and predictive value regarding recurrence risk and extended endocrine therapy benefit. One-way ANOVA assessed the relationship between disease grade, stage, and BCI scores, and an independent t-test identified the significance of grade 3 disease with higher mean BCI scores. Results: Grade 3 disease was associated with a significantly higher mean BCI score compared to lower-grade disease (11.03 vs. 5.18; p<0.001, independent t-test). One-way ANOVA showed strong correlations between both grade and stage of disease and BCI scores, with stage 3 patients having the highest mean score (12.03) compared to stage 1 (4.88) and stage 2 (7.74) patients (p<0.001) (Table 1). ER/PR/HER2 status also significantly influenced BCI scores (p<0.001), with ER+/PR+/HER2+ tumors showing the highest scores (15.20), followed by ER+/HER2+ (10.20) and ER+/PR+/HER2- (4.68). Conclusions: This study underscores the role of the Breast Cancer Index (BCI) in stratifying recurrence risk and guiding treatment in premenopausal women with hormone receptor-positive breast cancer. The ability of BCI assay to differentiate risk by grade, stage, and receptor status may refine treatment approaches and inform future guidelines. Larger studies with extended follow-up are needed to validate these findings and expand the clinical applications of BCI, particularly in diverse premenopausal populations and across ER/PR/HER2 receptor variations. Association of tumor grade and stage with mean BCI scores in premenopausal breast cancer patients. Grade Number of Patients Mean BCI Standard Deviation P-value 1 26 4.15 2.45 <0.001 2 54 5.68 3.48 3 18 11.03 4.53 Stage 1 58 4.88 2.64 <0.001 2 37 7.74 5.08 3 4 12.03 3.59 A one-way ANOVA analysis demonstrated a significant correlation (p < 0.001); higher tumor grade and advanced stage are associated with elevated BCI scores.