Altered fractionation: rationale and justification for whole and partial breast hypofractionated radiotherapy.

Over the last 2 decades, we have seen major advances in the application of radiotherapy after breast-conserving surgery. Two important contributions are the use of whole-breast hypofractionation and accelerated partial-breast irradiation. Three large randomized trials comparing whole-breast hypofractionation versus conventional fractionation for early breast cancer have shown similar rates of local recurrence and morbidity. As a result, whole-breast hypofractionation is now an option for selected patients after breast-conserving surgery. The delivery of accelerated partial-breast irradiation (APBI) has been studied using techniques of multicatheter interstitial brachytherapy, balloon-based brachytherapy, external-beam radiotherapy, and intraoperative radiotherapy. Multiple single and multi-institutional data have been published indicating good long-term results with APBI (in highly selected, low-risk patients) in terms of tumor control and toxicity. However, the long-term results of large, phase III trials comparing APBI with whole-breast irradiation are still pending.