Timing of radiotherapy in breast cancer conserving treatment.

The optimal timing and sequencing of adjuvant radiotherapy and chemotherapy after breast-conserving surgery for early invasive breast cancer is controversial. Several studies demonstrated that postoperative radiation therapy significantly reduces the incidence of breast recurrences. For patients who do not need systemic treatment, the interval between surgery and the start of radiotherapy should not exceed eight weeks. For node-positive and high-risk patients receiving breast-conserving treatment, adjuvant chemotherapy should be administered prior to radiotherapy, but the delay of radiation should not exceed 20-24 weeks. Side effects and complications of radiotherapy can be expected to increase when chemotherapy is administered concurrently. In particular, antracycline-based chemotherapy regimens increase the damage to heart muscle and coronary arteries: to avoid the risk of ischemic cardiovascular disease, radiotherapy must be performed after the end of systemic treatment.