The DBCG Proton Trial: Photon Versus Proton Radiation Therapy for Early Breast Cancer

Inclusion Criteria: * Patient operated for early breast cancer with indication for radiation therapy, where standard planning shows a mean heart dose 4 Gy or more and/or a V20 lung of 37% or more. * Boost (breast, chest wall and nodal), breast reconstruction (any type, except implants with metal), connective tissue disease, post-operative surgical complications, any breast size and seromas are allowed * Patient with previous non-breast malignancy is accepted if the patient has been without disease minimum 5 years, and the treating oncologist estimates a low risk of recurrence. * Life expectancy minimum 10 years Exclusion Criteria: * previous breast cancer/ductal carcinoma in situ, * Previous RT to the chest region * Pregnant or lactating * Conditions indicating that the patient cannot go through the RT or follow up * Patients with Pacemaker or defibrillator are excluded until a guideline for handling them has been developed at the DCPT * Unknown non-tissue implants upstream of the target volume. NB. all such non-tissue, non-metal objects must be delivered to the DCPT for stopping power determination and evaluation at least a week prior to radiation start. * Metal implants in the radiation area, including metal in implants.