Invasive Breast Cancer Early Stages

The goal of this clinical trial is to find out whether using a personalized breast holder (called VENUS SHELL™) can improve positioning and patient comfort during prone radiotherapy (radiotherapy given while the patient lies on her stomach). The main goals of the study are: * To confirm that using the VENUS SHELL™ is safe and effective * To assess whether the VENUS SHELL™ helps deliver accurate radiation treatment in a faster and more comfortable way Participants will: * Attend a study visit before radiotherapy to have a breast surface scan (no radiation) and enable the production of their personalized VENUS SHELL™ * Use their VENUS SHELL™ during radiotherapy planning and treatment * Be asked to complete questionnaires about their comfort

This is a multicenter, cohorts study to collect information from patients diagnosed with early-stage invasive breast cancer who have been previously included in a neoadjuvant or adjuvant clinical trial of the GEICAM group. Patients will be included in this study from the moment of completion of the follow-up of the studies of origin and will be followed for approximately 30 years