Beginning in the late 1970s, multiple randomized trials established the equivalence of breast-conserving surgery plus radiotherapy to mastectomy.1 Uncertainty existed with regard to the required radiation dose, as some of the early trials delivered an additional boost of radiation to the tumor bed after whole-breast radiotherapy while others did not.
In an effort to determine the optimal dose of radiotherapy after breast-conserving surgery, the European Organization for Research and Treatment of Cancer (EORTC) conducted a trial between 1989 and 1996.2 They randomized 5569 patients treated with breast conservation surgery followed by whole breast radiation to 50 Gy to no boost vs an additional 16 Gy directed to the tumor bed. At 20 years of follow-up, the risk of ipsilateral breast tumor recurrence (IBTR) was significantly reduced (hazard ratio, 0.65; P < .001) with the addition of a boost. The largest absolute benefit was seen in younger patients.2
Cuttino LW, Kubicky CD. Who Benefits From a Tumor Bed Boost After Whole-Breast Radiotherapy?. JAMA Oncol. 2017;3(1):21-22. doi:10.1001/jamaoncol.2016.3137