HYPofractionated Adjuvant  RadioTherapy in 1 versus 2 weeks in high-risk patients with breast cancer (HYPART):A non-inferiority, open-label, phase III randomized trial.

Abstract Background To test a 1-weeks chedule of hypofractionated adjuvant whole breast/chest wall and/or regional nodal radiotherapy against 2 weeks for loco-regional control, acute and late toxicities, quality of life (QoL), survival and second cancers after primary surgery in patients with breast cancer. Methods Eligible patients with breast cancer after mastectomy or BCS will be treated with a radiotherapy dose of 26Gy in 5 fractions over 1 week in the study arm and 34Gy in 10 fractions over 2 weeks in the control arm. The primary endpoint of this noninferiority study will be locoregional tumour control. Secondary endpoints will be early and late radiation toxicities, quality of life, contralateral primary tumours, regional and distant metastases, survival and second cancers. A total of 1018 patients will be randomised (1:1) to receive 1 week or 2 weeks of radiotherapy. An event-driven analysis will be performed after at least 94 patients have documented locoregional recurrences. Acute radiation toxicity will be assessed and scaled according to the RTOG grading system. Late radiation toxicity will be assessed with the Radiation Therapy Oncology Group and the European Organisation for Research and Treatment of Cancer late radiation morbidity scale. Cosmetic assessment will be done using Harvard/NSABP/RTOG breast cosmesis grading scale at baseline, 3 and 5 years. Quality of life (QoL) will be assessed with EORTC QLQ -30, EORTC QLQ-BR 23 at baseline, 3 and 5 years. Discussion Patients with breast cancer after mastectomy or BCS will be treated with a radiotherapy dose of 26Gy in 5 fractions over 1 week in the study arm and 34Gy in 10 fractions over 2 weeks in the control arm. Hypofractionation reduces treatment time to half while maintaining cosmesis and gives control rates equal to conventional fractionation. As breast cancer is a leading cancer in females and radiation therapy is an important part of its local management, hypofractionation helps radiation centres worldwide to meet the growing need for radiation treatment in breast cancer, particularly in developing countries where resources are limited. It also reduces the financial burden on the patient and family. Trial registration The trial is registered with ClinicalTrials.gov ID NCT04472845 and CTRI with REF/2020/09/037050.