Early-stage breast cancer Irradiation: who, when, where and how long?

Background In early-stage breast cancer, breast-conserving surgery is usually performed. This also includes an adjuvant radiotherapy, which for decades was administered daily over a period of 5-7 weeks. Whole-breast irradiation with or without a boost was standard practice. Objective An evidence-based review to determine who should be irradiated, when, where and for how long. Material and methods A systematic literature review of the relevant articles published in PubMed and in other databases between 2004 and 2021 was performed. Results After breast-conserving surgery, adjuvant radiotherapy of the breast results in a significantly reduced local recurrence rate. The current irradiation concept is moderately hypofractionated. In the case of very low recurrence risk and/or old age, partial breast irradiation or in selected subgroups ultra-hypofractionated irradiation schedules can be used. Otherwise, a boost can be administered to reduce the risk of local recurrence in higher risk patients. Conclusion Essentially, adjuvant radiotherapy after breast-conserving surgery is a well-studied technique with few side effects, which can reduce the risk of local recurrence by a factor of 3. Various concepts and techniques are available for individualized treatment. Overall, there is a trend towards de-escalation of radiotherapy in early-stage breast cancer.