Closeup Circulating tumor DNA in early-stage

breast cancer: personalized biomarkers for occult metastatic disease and risk of relapse? Taija M af Hällström*, Maija Puhka * & Olli Kallioniemi The availability of blood-based markers to predict response of a solid tumor to treatment, estimate patient prognosis and diagnose relapse well before clinical symptoms arise, is a long-standing hope in clinical oncology. Ideally, assays designed to provide such information should be inexpensive (at least in the foreseeable future), simple, and, of course, predictive of the clinical evolution of the disease. While early research focused on circulat