Comparing the Combination of Clinical Risk and Ki-67 Using EndoPredict as an Alternative to Multigene Assays in Prognostic Evaluation of Breast Cancer

Abstract

Purpose

Many studies have examined the relationship between prognostic factors and multigene assays; however, their use as alternatives remains insufficient. This study evaluated the concordance of the combination of clinical risk (CR)—which was determined using the modified version of Adjuvant! Online—and the Ki-67 index using EndoPredict (EP).

Methods

Retrospective data from 709 patients were analyzed. The diagnostic accuracy, including concordance, was assessed between CR and EP (EPclin risk vs. EP risk), along with the Ki-67 index (cut-off: 20%). The clinical significance was analyzed using an area under the receiver operating characteristic (ROC) curve.

Results

EPclin risk showed higher concordance with both CR and Ki-67 than EP risk, and CR showed higher concordance with both EPclin and EP risk than Ki-67. Differences in concordance with CR based on Ki-67 were limited; however, the negative predictive value (NPV) increased in the Ki-67 < 20% group (86.9% in EPclin), whereas the positive predictive value (PPV) increased in the Ki-67 ≥ 20% group (82.7% in EPclin). Improvement in PPV and NPV, as well as concordance, was observed with EPclin in 447 patients with high CR/high Ki-67 and low CR/low Ki-67. ROC analysis confirmed the clinical significance of combining CR with the Ki-67 index, as their combined area under the curve increased to 0.794, compared to 0.660 for CR and 0.742 for Ki-67 alone in EPclin risk.

Conclusion

Integrating CR with the Ki-67 index improves prognostic accuracy and provides a cost-effective alternative to the EP test for luminal-type early breast cancer.