Breast cancer is the most common form of cancer among women. Five to ten percent of all breast cancers are due to hereditary factors, with pathogenic variants in the breast cancer genes BRCA1/2 accounting for 2-5% of all breast cancer. Women with pathogenic variants in BRAC1/2 and other pathogenic gene mutations leading to an increased risk of breast cancer can undergo prophylactic mastectomy, reducing the risk of breast cancer up to 90%. Among women who have undergone prophylactic mastectomy, 1-1,9% are diagnosed with breast cancer, but little is known about the correlation between residual glandular tissue and skin flap thickness, as well as the oncological risk of residual glandular tissue. Furthermore, there is a balance between how much subcutaneous tissue should be resected to achieve maximal reduction of glandular tissue, while leaving viable skin flaps. In addition, there are established surveillance guidelines for women with pathogenic variants in BRCA1/2 who do not undergo risk-reducing surgery, but no published consensus or guidelines regarding appropriate medical follow-up for those who opt for prophylactic mastectomy. The aim of this study is to investigate the correlation between skin flap thickness, residual glandular tissue and skin flap necrosis following prophylactic mastectomy in women with results from postoperative magnetic resonance tomography, ultrasound and physical examination, as well as evaluate patient satisfaction and quality of life pre- and postoperatively with different questionnaires.