Association between ki67 antigen and other clinicopathological factors with the Oncotype DX Score in luminal breast cancer

Introduction: Luminal tumors show molecular differences and different behavior. The antigen Ki67 is one of the factors that differentiate between luminal A and B. Genomic platforms can identify which patients will benefit from chemotherapy. Objectives: To establish if there is an association between ki67 and Oncotype Dx Score (RS). To assess the influence of ki67 and RS on the therapeutic decision, to evaluate the association between clinical risk and RS, between lymphovascular invasion (LVI) and RS, and between positive axillar nodes (up to 1 node) and RS. Materials and methods: Retrospective, observational, descriptive study. We included 68 patients with negative Her2Neu luminal tumors, T1-T2, negative or positive axillary up to 1 node, who performed Oncotype DX between 2009 and 2020 at Hospital Alemán. They were classified into RS less than or equal to 25 and greater than 25 based on the TAILORx study, where it was shown that overall there is no benefit from chemotherapy between 0-25. Results: An association was observed between ki67 and RS in 44 (64.7%) patients and it was greater between low ki67 and RS less than or equal to 25 (77.3%). The treatment was based on RS. An association between clinical risk and RS was observed in 43 (63.2%) patients, and it was greater between low clinical risk and RS less than or equal to 25 (87.5%). In 88.8% there was no association between LVI and RS, as well as between positive axillary up to 1 node and RS in 85.7%. Conclusion: It is necessary to offer every patient with a luminal tumor a genomic platform since both ki67 and other pathological clinical factors alone did not prove to be superior or sufficient.