NanoString Technologies announced that Annals of Oncology, the journal of the European Society of Medical Oncology, has published a pivotal study validating the Prosigna Breast Cancer Prognostic Gene Signature Assay for predicting the risk of distant recurrence in postmenopausal women with Hormone Receptor-Positive early-stage breast cancer. The study was based on an analysis of the Austrian Breast & Colorectal Cancer Study Group 8 trial and concluded that patients categorized by the Prosigna Assay as low risk are unlikely to benefit from additional chemotherapy. As a result of the authors independently replicating the results of the recently published TransATAC study, this study also showed that the Prosigna Assay has achieved Level 1 Evidence, the standard typically required for inclusion in cancer treatment guidelines. The aim of this study was to assess the performance of the ROR score, also known as the Prosigna Score, in estimating distant recurrence-free survival in postmenopausal women with HR+ early-stage breast cancer treated with adjuvant systemic endocrine therapy alone when the assay is performed in a hospital molecular pathology lab. Investigators at the British Columbia Cancer Agency performed the Prosigna Assay on archived formalin-fixed paraffin embedded tumor samples from 1,620 participants in ABCSG-8 using the nCounter Dx Analysis System installed in BCCA’s Center for Translational and Applied Genomics.