hypofractionation with simultaneous integrated boost vs. standard fractionation in early breast cancer

Conditions: Early-Stage Breast Carcinoma

Summary: 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.

Eligibility criteria:
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

Keywords: breast cancer hypofractionation with sib non-inferiority adjuvant radiotherapy with simultaneous integrated boost