Cancer du sein au stade précoce : stopper la désescalade en radiothérapie

Radiotherapy (RT) remains a major treatment element in early breast cancer, with a major impact on local control and survival. For ductal carcinoma in situ (DCIS), RT reduces local recurrence (LR) rates by 50 to 60 % after conservative surgery (both in situ and invasive). This was confirmed by four randomized trials and one meta-analysis. For infiltrating breast cancers (IBC), RT also reduces LR rates by 65 to 75 % after conservative surgery. Boost allows an additional reduction of LR. RT is efficient in all age categories, but hypofractionated schemes are particularly adapted to elderly women. Partial breast irrradiation techniques are very much heterogeneous and lack follow-up. They should be used in LR low-risk patients only and in the frame of controlled studies. Locoregional RT for high-risk patients (especially in pN +) remains essential to reduce the locoregional recurrence rate and to increase survival, as confirmed in several meta-analyses. Four studies showed a survival benefit (2-3 %), thanks to internal mammary chain irradiation in LR high-risk patients. Moreover, axillary RT seems to be a likely valuable alternative to axillary dissection in case of sentinel node invasion. Finally, with the modern techniques and dosimetric optimization, RT toxicity was reduced, or even cancelled, arousing hope for a better increased benefit for the patients in the future.