Impact of deep inspiration breath-hold and fractionation on immune system exposure in breast radiotherapy

DIBH significantly reduces the dose to the immune system by 10% in cases of locoregional irradiation of right breast cancers, and moderate hypofractionation results in an EDIC gain compared with any standard fractionation treatment. Pending formal demonstration of a relationship between dose to the immune system and survival, as is the case in other localizations, we suggest as a precaution the use of DIBH combined with hypofractionated treatment in cases where immune sparing seems most important, such as breast cancers with a poor response after preoperative immunotherapy.