Advances in molecular testing have ushered in the new era of precision medicine. The 2018 publication of the TAILORx trial helped refine the use of genetic expression assays, specifically the 21-gene recurrence score, in assigning patients to endocrine therapy alone or with chemotherapy. The NCCN Guidelines for Breast Cancer explore the clinical applications of this study. The algorithm for managing the axilla in early breast cancer has been further refined, based on the presence or absence of clinical evidence of lymph node involvement. Ovarian suppression has been validated as the optimal approach in higher risk premenopausal women, based on updated analysis of the SOFT and TEXT pivotal trials. In the metastatic setting, the NCCN Guidelines further reinforce the benefit of the CDK4/6 inhibitors, extending the "preferred" recommendation to all the available agents in metastatic disease. Options in triple-negative breast cancer now include, for the first time, an immunotherapeutic agent.