This trial is to investigate whether pre-pectoral Implant-Based Breast Reconstruction (IBBR) provides better Quality of Life (QoL) with respect to long-term (24 months) physical well-being (chest) compared to sub-pectoral IBBR for patients undergoing skin-sparing mastectomy or nipple-sparing mastectomy for prevention or treatment of breast cancer.The aim is to adhere to standard of care as much as possible to follow the pragmatic trial design to generate data that are applicable to today's practice. Therefore, surgeons are allowed to use their preferred Acellular Dermal Matrix (ADM), synthetic meshes, expanders and implants, thereby offering practitioners considerable leeway in deciding how to perform the procedure. For the same reason, both the one- and two-staged IBBR approaches are allowed when studying pre- versus sub-pectoral IBBR.