The addition of adjuvant chemotherapy to hormonal therapy is often considered questionable
in patients with estrogen receptor-positive early breast cancer. Low risk of disease relapse
after endocrine treatment alone and/or a low sensitivity to chemotherapy are reasons behind not all
patients benefit from chemotherapy. Most of the patients could be exposed to unnecessary treatment-
related adverse events and health care costs when treatment decision-making is based only on
classical clinical histological features. Gene expression profile has been developed to refine physician’s
decision-making process and to tailor personalized treatment to patients. In particular, these
tests are designed to spare patients the side effects of unnecessary treatment, and ensure that adjuvant
chemotherapy is correctly recommended to patients with early breast cancer. In this review,
we will discuss the main diagnostic tests and their potential clinical applications (Oncotype DX,
MammaPrint, PAM50/Prosigna, EndoPredict, MapQuant Dx, IHC4, and Theros-Breast Cancer
Gene Expression Ratio Assay).
Validation of the American Joint Committee on Cancer new prognostic stage groups for HER2-positive breast cancer patients treated with adjuvant chemotherapy and trastuzumab in the prospective ShortHER trial
