In the Era After the European Organisation for Research and Treatment of Cancer 'Boost' Study, is the Additional Radiotherapy to the Breast Tumour Bed Still Beneficial for Young Women?

•Prior to routine hormone therapy (HT) use, a boost (RTB) reduced breast cancer local recurrence in women ≤ 40 years.•The use of HT and RTB increased significantly after the introduction of new practice guidelines.•Local recurrence was halved after introduction of the HT guideline.•No improvement in local recurrence was associated with the introduction of the RTB guideline in the HT era.•The routine use of RTB in unselected young women with negative margins should be re-evaluated in the current HT era.