Hypofractionation with simultaneous integrated boost has been investigated in a few trials and appears to be safe and feasible with less lung toxicity in smaller studies.

Investigators initiated this multicenter phase II prospective trial to analyse acute toxicity of hypofractionation with simultaneous integrated boost in patients with early breast cancer under the hypothesis that the ratio of patients with acute radiogenic toxicity Grad II according NCI-CTCAE amounts maximum 20%.

Hypofractionated radiotherapy of the breast 16 × 2.50 Gy with simultaneous integrated boost to the tumor bed (total dose within the boost volume 16 × 3.00 Gy).

Inclusion Criteria:

• Histopathologically confirmed breast cancer operated by breast conserving surgery with clear margins
• Indication to adjuvant radiotherapy including boost radiotherapy
• Clearly identified primary tumor region preferably by radiopaque clips
• Primary wound healing after breast conserving therapy without signs of infection
• Pre- and/or postoperative chemotherapy and endocrine therapy were permitted when indicated
• Written informed consent

Exclusion Criteria:

• Patients operated by mastectomy
• No indication for boost radiation
• Resection margins positive for disease or insufficient identification of the boost volume
• Indication for radiotherapy of the regional lymph nodes
• History of prior breast or thoracic radiotherapy
• Extended postoperative seroma at the beginning of radiotherapy
• Psychiatric disorders or psychological disabilities thought to adversely affect treatment compliance
• Pregnant or lactating patients and woman of child bearing potential, who lacked effective contraception