E01. Striving for the optimum

Abstract

The treatment of early breast cancer has changed drastically, from avoidance of mastectomy to preoperative partial breast irradiation, and to an individualized approach for adjuvant treatment. These changes became possible as a result of the inclusion of modern imaging before and during surgery and radiotherapy, and by selecting adjuvant treatment on prognostic and (soon) predictive molecular biological assays. All this has led to a major improvement in treatment outcomes, as shown by the results from several trials performed over recent decades. These trials have led us to ask new questions: in particular, how will molecular biology guide the treatment of early breast cancer towards precision medicine? An intriguing issue is the age effect in breast cancer patients. Although long-term follow-up has revealed that mastectomy results in survival equal to that of breastconserving therapy (BCT) [1], the boost versus no boost trial showed a dramatic age effect in young patients in that they had many more local recurrences than older patients [2] (Fig. 1). This trial aimed at reducing the required radiation dose for BCT, weighing the side effects (i.e. fibrosis) against improved tumor control. Fortunately it was shown that younger patients benefited from a higher radiation in the European Organisation for Research and Treatment of Cancer (EORTC) boost versus no boost trial, while in older patients a lower radiation dose was sufficient [3] (Fig. 2).