Validation of a Clinical-Genomic Model for Patients With Early-Stage Breast Cancer Enrolled in a Taiwanese Multicenter Study

Abstract

BackgroundNumerous prospective studies, predominantly in the Caucasian population, have proven the clinical utility of using multigene expression tests to prevent overtreatment in early-stage breast cancer patients with early-stage disease. In this study, we used an Asian population to validate a clinical-genomic assay (RecurIndex®) for estimating the risk of distant recurrence and relapse in early-stage breast cancer patients. MethodsA total of 298 patients with early-stage breast cancer, luminal-like subtype (85.6%) and HER2-enriched/ triple-negative subtype (14.4%), was enrolled in a retrospective study across five participating medical centers in Taiwan. The inclusion criteria were as follows: women (1) who underwent primary surgery without prior induction treatments, (2) with an early pathologic N stage and (3) who received either mastectomy or breast-conserving surgery. Kaplan Meier method and Cox proportional hazards model were used to, respectively, identify independent prognostic factors and calculate the 5- and 10-year survival rates of patients in the low- and high-risk groups assigned by the diagnostic test. A forest plot was produced to assess hazard ratios and 95% confidence intervals. The primary endpoint was distant recurrence-free survival (DRFS) and the secondary endpoint was relapse-free survival (RFS).ResultsThe 10-year DRFS rate was significantly higher in the good prognosis group than in the poor prognosis group (91.9% [95% CI, 86.1-98.1%] versus 62.9% [95% CI, 49.8-79.4%]). The overall hazard ratio for distant recurrence was 1.031 [95% CI, 1.017 - 1.046] per unit Recurrence index-distant recurrence (RI-DR) score increment. ConclusionsThe present study provides robust evidence of the clinical utility of using the RI-DR score to accurately predict clinical outcomes. RecurIndex® could be used to determine the utility of adjuvant chemotherapy in Asian patients, especially those having hormone-receptor positive tumors, leading to a meaningful reduction in adjuvant chemotherapy recommendations.