Molecular Signatures Predict Outcomes of Breast Cancer

Breast cancer is classified and managed largely on the basis of anatomy — in contrast with lymphoma, which has been classified and treated according to grade for more than 20 years. Tumor size and the degree of involvement of the axillary nodes are used to estimate the risk of systemic micrometastases at diagnosis and, accordingly, whether systemic adjuvant therapy, which improves overall survival in largely unselected populations, is needed.1 A routine question faced by oncologists is, which of the two thirds of patients with hormone-receptor–positive breast cancer require systemic adjuvant chemotherapy to decrease their chance of recurrence? Although there are . . .