Independent prognostic value of the gene-only BCT Score compared with the 21-gene recurrence score in ER+/HER2-early breast cancer

Abstract

Background: The GenesWell BCT is a prognostic assay that integrates the expression of six prognostic and three reference genes with clinicopathological factors (tumor size and nodal status) to generate a BCT Score. The BCT Score is used to predict the risk of recurrence in early breast cancer. We excluded clinical variables and developed a gene-only version of the BCT Gene Score to evaluate its independent prognostic performance. Methods: We assessed the prognostic value of the BCT Gene Score in a cohort of patients with ER+/HER2- early breast cancer using available Oncotype DX Recurrence Score (RS) data. The primary endpoint was concordance between the assays and recurrence-free survival (RFS). Results: We analyzed 759 samples from five Korean institutions. Risk classification concordance between the BCT Gene Score and the BCT Score was 81.2%, whereas concordance with the Oncotype DX RS was 74.2%, indicating moderate agreement. All three scores were significantly associated with RFS (p < 0.05). Combining the BCT and BCT Gene Scores improved prognostic stratification compared with either score alone. Patients classified as high risk by both scores exhibited the poorest prognosis, whereas those classified as low risk by both scores exhibited the most favorable outcomes. Among patients with low RS, those reclassified as high risk by the BCT Gene Score exhibited significantly worse RFS. Conclusions: The BCT Gene Score exhibits independent prognostic utility and complements the original BCT Score. Risk stratification may be enhanced by incorporating both scores, ultimately guiding more precise treatment decisions in ER+/HER2- early breast cancer.