Tailoring Chemotherapy in Early-Stage Breast Cancer: Based on Tumor Biology or Tumor Burden?

The question of whether to offer adjuvant chemotherapy to patients with early-stage breast cancer has always been challenging to answer. It is well known that a substantial proportion of patients with early-stage breast cancer are over treated, especially when staging and hormonal and HER2 receptors are solely taken into consideration. The advances in our knowledge of breast cancer biology and its clinical implications were the basis for the discovery of additional reliable prognostic markers to aid decision making for adjuvant treatment. Gene expression profiling is a molecular tool that more precisely defines the intrinsic characteristics of each individual tumor. The application of this technology has led to the development of gene signatures/profiles with relevant prognostic—and some predictive—value that have become important tools in defining which patients with early-stage breast cancer can be safely spared from chemotherapy. However, the exact clinical utility of these tools will only be determined after the results of two large prospective randomized trials, MINDACT and TailorX, evaluating their role become available. Notwithstanding the existence of these genomic tools, tumor burden (defined as tumor size and nodal status) still has independent prognostic value and must be incorporated in decision making. In addition, these gene signatures have limited predictive value, and new biomarkers and new targets are needed. Therefore close collaboration between clinicians and scientists is crucial. Lastly, issues of cost-effectiveness, reimbursement, and availability are crucial and widely variable around the globe.