In this article, we review the current status, indication, technical aspects,
controversies, and future prospects of boost irradiation after breast conserving
surgery (BCS). BCS and radiotherapy (RT) of the conserved breast became widely
accepted in the last decades for the treatment of early invasive breast cancer.
The standard technique of RT after breast conservation is to treat the whole
breast up to a total dose of 45 to 50 Gy. However, there is no consensus among
radiation oncologists about the necessity of boost dose to the tumor bed.
Generally accepted criteria for identification of high risk subgroups, in which
boost is recommended, have not been established yet. Further controversy exists
regarding the optimal boost technique (electron vs. brachytherapy), and their
impact on local tumor control and cosmesis. Based on the results of numerous
retrospective and recently published prospective trials, the European
brachytherapy society (GEC-ESTRO), as well as the American Brachytherapy Society
has issued their guidelines in these topics. These guidelines will help
clinicians in their medical decisions. Some aspects of boost irradiation still
remain somewhat controversial. The final results of prospective boost trials with
longer follow-up, involving analyses based on pathologically defined subgroups,
will clarify these controversies. Preliminary results with recently developed
boost techniques (intraoperative RT, CT-image based 3D conformal brachytherapy,
and 3D virtual brachytherapy) are promising. However, more experience and longer
follow-up are required to define whether these methods might improve local tumor
control for breast cancer patients treated with conservative surgery and RT.