Accelerated Partial Breast Irradiation Using External Beam Volumetric Modulated Arc Therapy (VMAT): a Randomised Non-inferiority Trial of 30 Gy Versus 26 Gy in Five Fractions Investigating Patient-reported Outcomes

Accelerated partial breast irradiation (APBI) will be delivered using Volumetric Modulated Arc Therapy (VMAT). Treatment will be started within 12 weeks of breast conserving surgery and within four weeks of randomisation. Treatment will occur in five (5) once-daily sessions and should be completed within seven (7) days of starting radiotherapy. Two total doses of APBI will be compared: 30 Gy and 26 Gy. The aim is to determine whether quality of life is no worse when a higher dose of APBI is used compared to a slightly lower dose of APBI. The results of this study will help to guide doctors choose the best dose of APBI for patients with early breast cancer in the future.