Gene Expression Analyses in Early Breast Carcinoma — Quo Vadis?

Abstract

In order to establish whether adjuvant therapy should be administered in patients with breast carcinoma, it is decisive to have as precise as possible an assessment of the risk of recurrence. In this context, gene expression — and thus gene expression signatures as well — have become a focus of attention as prognostic factors. For practical application, it is important to be able to analyze gene expression signatures in formalin-fixed, paraffin-embedded tumor tissue. Careful analytic and clinical validations and a high level of evidence (LoE) are required in order to avoid imprecise risk classification and thus potential overtreatment or undertreatment of the patients. Among the commercially available gene expression signatures, the Working Group on Gynecological Oncology (Arbeitsgemeinschaft Gynäkologische Onkologie, AGO) currently grades MammaPrint® and Oncotype DX® as having LoE IA, with prospective study results; and Endopredict® and Prosigna® as having LoE IB. The panel members at this year’s St. Gallen consensus conference also voted by a majority in favor of the possible usage of Oncotype DX®, MammaPrint®, Prosigna®, EndoPredict®, and Breast Cancer Index®. These multigene tests can be used in selected patients with hormone receptor–positive and HER2-negative findings if none of the other criteria allow a treatment decision to be made.