Comparison of Mastectomy Expander Trial

Inclusion Criteria: * Understands and agrees to comply with the study procedures and provides informed consent as documented by signature * Female subjects aged ≥ 18 years at time of consent * INDICATION: Breast cancer diagnosis (malignancy) with neoadjuvant chemotherapy OR ductal carcinoma in situ (DCIS) diagnosis without neoadjuvant chemotherapy AND / OR positive genetic counseling for high-risk family history of breast cancer * RECONSTRUCTION MODALITIES: planned uni- or bilateral NSME or SSME with simultaneous prepectoral tissue expander-based breast reconstruction due to malignancy OR Planned prophylactic bilateral mastectomy with simultaneous prepectoral tissue expander-based breast reconstruction. Planned unilateral NSME or SSME and planned prophylactic contralateral mastectomy with simultaneous prepectoral tissue expander-based breast reconstruction * Ability to speak and read German to a level which allows fully comprehending the meaning of everything that is said or written. * Inclusion criterion 6 only applies to subject with radiotherapy: Adjuvant radiotherapy as part of the breast cancer treatment plan * Inclusion criterion 7 only applies to women of childbearing potential (WOCBP): negative urine pregnancy test, not breastfeeding Exclusion Criteria: * Subject with implanted device that may be affected by magnetic fields (pacemaker) * Known presence of HIV, viral hepatitis (patient-reported) * Presence of autoimmune disease(s) or immunocompromised subject due to immunosuppressive or steroid therapy * The subject is currently participating or intends to participate in another clinical trial that may interfere with the protocol of this study.