MammaPrint can be used to guide clinical decisions and is included in the majority of BC clinical guidelines with the highest level of evidence, including the NCCN algorithm with a level of evidence 1 as a prognostic tool in HR-positive, HER2-negative breast cancer with up to 3 positive nodes [94], ASCO [95], ESMO [96] and AGO [98]. Here, ERBB2 is linked to breast cancer.