Clinicians increasingly recognize the problem of overtreatment in medical care. Overtreatment is particularly a concern for cancer conditions that are targeted for early detection because screening results in a large population of patients with early-stage disease. Patients with early-stage disease may experience overtreatment because the cumulative morbidity and adverse consequences on quality of life of cancer therapies are often substantial, but the benefit of each single modality can be very small and uncertain in an individual patient. For example, the net 10-year survival benefit of chemotherapy for patients with node-negative, hormone-receptor positive, ERBB2-negative (formerly HER2 or HER2/neu) breast cancers smaller than 2 cm is less than 4%.1 Prior to the advent of genomic expression testing, professional consensus guidelines for treatment diverged from those of a National Institutes of Health/Centers for Disease Control and Prevention panel strongly recommending adjuvant chemotherapy in these patients, whereas an international panel was not supportive of this approach.