Gene-expression profiles in adjuvant treatment of early breast cancer

Breast cancer is a heterogeneous disease with different subtypes having a distinct biological, molecular, and clinical course. Assessments of standard clinical and pathological features have traditionally been used to determine the use of adjuvant systemic therapy in early-stage breast cancer; however, the ability to identify those who will benefi t from adjuvant chemotherapy remains a challenge, leading to over treatment of some patients. Risk stratifi cation of patients with early stage breast cancer may support adjuvant chemotherapy decision-making. This review details the development and validation of seven multi-gene classifi ers, each of which claims to provide useful prognostic and possibly predictive information for early stage breast cancer patients. A careful assessment is presented of each test’s analytical validity, clinical validity, and clinical utility, as well as the quality of evidence supporting its use.