Innovation in adjuvant radiotherapy for breast cancer: new biologic parameters, a perspective for treatment tailoring

In the adjuvant setting, whole breast radiation therapy (RT) delivering 50 Gy in 5 weeks with or without a boost to the tumor bed remains the standard of care. RT indications and volume definition are generally dependant on existing prognostic factors. Except in particular cases, RT technique does not vary according to the patient or tumor biology profiles in terms of total dose, dose per fraction, fractionation, and RT duration. The challenge is to define new parameters or tumor biology profiles that will allow patient selection for more tailored RT than the 5 to 7 week standard schedules. The future issue is to define biological markers able to screen patients and tumors according to their high metastatic potential (in which the primary therapeutic challenge may not be locoregional control) and those patients that have a particular radiosensitivity to ionizing radiation for higher benefit/risk ratio. Thus, it is probable that patient profiles, tumor biology markers and gene expression profiling could provide in future an added value to conventional markers to predict patients at high-risk of local and distant recurrences who need tailored treatment or a particular sequence of adjuvant therapy.