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Updated: Jul 11, 2026
Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material
Published on: August 1, 2018
High Ki-67 expression is associated with increased risk of distant recurrence in Oncotype Dx low risk breast cancer
Soumaya Labidi1, Nasser Mulla2, Islam E Elkholi3
1Segal Cancer Center, Jewish General Hospital, Montréal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Montréal, Quebec, Canada.
Purpose:
To assess whether high Ki-67 protein expression level could independently predict the distant recurrence in early-stage breast cancer with low Oncotype Dx scores (≤ 25).
Methods:
This single-center retrospective cohort study included 278 patients with hormone receptor positive (HR+) human epidermal growth factor receptor 2 negative (HER2-), T1-2N0M0, low Oncotype Dx recurrence score (RS) (≤ 25) breast cancer. We identified 2 groups: "high Ki-67″ ≥ 15% (n = 130, 47%) and "low Ki-67″ < 15% (n = 148, 53%). Clinical characteristics, treatment and survival were abstracted from chart review. Fisher's exact test was used to assess differences between Ki-67 groups. Cox-regression models were used to assess differences in survival.
Results:
After a median follow up of 7 years, 13 (4.7%) patients experienced distant metastasis. Recurrence rate was significantly higher in the "high Ki-67″ group 9.2% (12/130) versus the "low Ki-67″ group 0.7% (1/148) (P = .001). Distant metastasis-free survival (dMFS) was significantly shorter in the "high Ki-67″ group (HR 12.90, 95% CI, 12.53-13.27, P = .008). Tumor size ≥ 2 cm was associated with shorter dMFS (HR, 12.90; 95% CI, 12.53-13.27; P < .001). In a multivariable analysis, tumor size ≥ 2 cm and "High Ki-67″ were independent prognosis factors for dMFS.
Conclusion:
Ki-67 expression level may help to identify a subset of low risk Oncotype Dx patients who could benefit from adjuvant chemotherapy.
