Breast reconstruction is offered to women after mastectomy with the aim to increase patient satisfaction and quality of life (QOL). In this research project, women were randomized to delayed breast reconstruction with either an autologous method, deep inferior epigastric perforator (DIEP) flap, or with an expander prosthesis (EP). This is the first randomized study to compare the two breast reconstruction methods. In the research project, we will investigate patient satisfaction, QOL, health care costs and clinical and cosmetic outcome after breast reconstruction.