Hypofractionation with simultaneous integrated boost has been investigated in a few trials and appears to be safe and feasible.

Investigators initiated this multicenter two-armed phase III prospective trial to analyse the non-inferiority of hypofractionation with simultaneous integrated boost in patients with early breast cancer in comparison to standard fractionation.

Control Arm:

Conventionaly fractionated radiotherapy of the breast 28 × 1.8 Gy = 50.4 Gy followed by a tumor bed boost sequentially 5 to 8 × 2.0 Gy = 10.0 Gy to 16.0 Gy, total dose 60.4 Gy to 66.4 Gy.

or Conventionaly fractionated radiotherapy of the breast 28 × 1.8 Gy = 50.4 Gy with simultaneous integrated boost to the tumor bed, total dose 28 × 0.3 Gy or 0.45 Gy= 8.4 Gy or 12,6 Gy, total dose 58,8 Gy to 63.0 Gy.

or Hypofractionated radiotherapy of the breast 16 × 2.66 Gy = 42.56 Gy followed by a tumor bed boost sequentially 5 to 8 × 2.0 Gy = 10.0 Gy to 16.0 Gy, total dose 52.56 Gy to 58.56 Gy.

Experimental Arm:

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 independently of further risk factors (positive or high-risk negative lymph node status, estrogen- or progesterone receptor status, Her-2/neu status uPA/PAI-1 criteria) and postoperative systemic therapy (chemotherapy, endocrine, antibody or bisphosphonate therapy were permitted when indicated)
• 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
• Age ≥ 18 years
• ECOG ≤ 2 Performance Status
• Written informed consent
• Compliance regarding treatment appointments and toxicity
• Linguistic and cognitive ability to understand the questionnaires

Exclusion Criteria:

• Patients operated by mastectomy
• No indication for boost radiation (e.g. status after IORT)
• double sided breast cancer
• 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
• Previously administered radiotherapy not allowing the required dose
• Pregnant or lactating patients and woman of child bearing potential, who lacked effective contraception
• treatment history of other cancer or participation in another clinical trial testing radiotherapy or drugs within 4 weeks of the start of treatment.
• Patients with serious, uncontrolled, physical or cerebrovascular disorders(e.g. myocardial infarction within the last 12 months) or neurologiy or psychiatric disorders thought to adversly affect treatment compliance