Preoperative Radiation Therapy and Immediate Breast Reconstruction

Screening assessments, including review of all study eligibility criteria must be completed before enrolment and randomisation. Inclusion criteria: In order to be eligible to participate in this study, a participant must meet all of the following criteria: 1\. Women ≥18 years with histopathologically confirmed breast cancer who: 1.a. require SSM/NSM for any reason (e.g. extensive disease) 1.b. require postoperative radiation therapy of at least the chest wall 1. c. have a wish for a breast reconstruction 2. An Eastern Cooperative Oncology Group (ECOG) performance status grade ≤ 2 3. Participant is able and willing to provide written informed consent, which includes compliance with and ability to undergo all study procedures, and attend the scheduled follow-up visit(s) per protocol. Exclusion criteria: A potential participant who meets any of the following criteria will be excluded from participation in this study: 1. A previous history of breast cancer or irradiation of the chest wall for any other indication, on the other side (ipsilateral). A bilateral SSM/NSM + reconstruction (e.g. in case of a contralateral prophylactic SSM/NSM), or previous contralateral breast cancer disease/treatment, do not fall under this criterium and are thus allowed. 2. Collagen synthesis disease 3. Ongoing pregnancy 4. Actively breastfeeding 5. Smoking at time of inclusion (a history of smoking is allowed but needs to be registered in the eCRF). No interval between smoking cessation and study inclusion is defined, but the reconstructive surgeon needs to be willing to operate the patient using autologous tissue transfer. This generally translates to a smoking cessation of \>3months preoperatively. 6. BMI \> 35 kg/m2 7. cT4d tumour, metastatic disease or any reason making SSM/NSM not indicated