Comparison of Mastectomy Expander Trial

Breast cancer-diagnosed patients and patients undergoing prophylactic mastectomy will undergo unior bilateral tissue expander breast reconstruction. Participants will be screened and only after the eligibility is confirmed, the patients will be included and randomized in either receiving prepectoral uni- or bilateral MRI-conditional: Arm 1 or Arm 2 TE. Within the first operation patients will receive an expander (=inflatable silicone implant) to increase the amount of tissue available for breast reconstruction. The expander is positioned in the subcutaneous plane combined with or without a GalaFLEX™ matrix, a biologically derived 2D scaffold.

The suture is removed (visit 2) and the expander is stepwise filled in 2-3 visits (visit 3 and 4, an optional visit 4b might be necessary).

The two study arms are further divided in subjects with adjuvant radiotherapy (collective I) or without adjuvant radiotherapy (collective II) according standard of care.

The decision regarding the adjuvant radiotherapy following breast implantation is be made by the surgeon and the radiation oncologist before inclusion into the study. If subjects from collective II need an adjuvant radiotherapy based on interdisciplinary tumorboard decision after OP 1 (pretherapeutical nodal + patients and/or on definitive histological findings in mastectomy specimens/axillary lymphnodes), subjects will switch from collective II to collective I.

After 6 months, the expander is removed and a permanent silicone breast implant is placed (exchange expander to definitive implant or autologous tissue; OP 2). Two clinical follow-up visits will be scheduled 12 and 24 months after the second operation.

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.