The goal of this clinical trial is to learn if nerve sutures in free flap breast reconstruction can optimize sensibility in the reconstructed breast in patients opting for DIEP flap breast reconstruction due to breast cancer or genetic conditions. Affected women 18 to 80 years old can be included. The main question is:

If a nerve suture was carried out, can pressure be felt better on the reconstructed breast after 12 months? If a nerve suture was carried out, will better sensibility and quality of life be felt and perceived (questionnaire) at 12 and 24 months after the initial operation ? Researchers will compare two different nerve suture techniques and no nerve suture to one another to see if and which nerve suture optimizes sensibility.

Participants will have regular visits and follow-up controls, during which

• their sensibility will be tested multimodally,
• they will fill out questionnaires
• skin biopsies will be taken.

Breast reconstruction with autologous tissue is one of the most important methods: The DIEP (deep inferior epigastric artery perforator) flap is today's workhorse in autologous reconstruction. Routinely, the arteries and veins of the donor- and recipient sites are connected, but not the nerves. The sensory recovery is an undervalued aspect despite the disadvantages of insensate flaps. Connection of the abdominal flap skin's nerves to the breast region's nerves allows sensitized reconstruction. The research project aims to make sensitized flap-based breast reconstruction the standard method by proving its superiority, using the sensory testing with Semmes-Weinstein-Monofilament (pressure threshold) as the primary outcome measured before surgery and 12 months post-surgery. Therefore, patients will be randomized in three groups:

1. sensitization with direct nerve suture or
2. autograft or
3. no sensitization. Moreover, no previous studies have analyzed the potential changes in flap skin with proteomics, thus justifying our secondary objective.

The hypothesis is that flaps with nerve suture(s) have better sensibility. The main outcome will be the sensory testing (pressure threshold). As secondary outcomes the questionnaire will show the patients' quality of life, and the proteomic analysis, should, according to our hypothesis, show that quantity and expression of the proteins of flap skin with nerve suture are closer to normal skin than without nerve suture.

A) Pilot study

Inclusion criteria:

• 18-80 years old
• having received DIEP flap breast reconstruction with a flap not completely buried
• having given written informed consent for participating in the study

Exclusion criteria:

• postoperative radiotherapy on the flap
• neurological conditions as diabetic neuropathy, alcoholism or any other severe underlying peripheral neuropathy including chemotherapy-induced neuropathy or neuropathy induced by other medications
• active smoking
• language barrier
• pregnancy or lactating women

B) Main study

Inclusion Criteria:

• 18 to 80 years old
• having given written informed consent for participating in the study
• receiving immediate or delayed unilateral DIEP breast reconstruction with a DIEP flap which will not be completely buried

Exclusion Criteria:

• autologous reconstruction where the flap is completely buried
• patients in need of both-sided reconstruction (double DIEP)
• postoperative radiotherapy on the flap
• neurological conditions as diabetic neuropathy, alcoholism, or any other severe underlying peripheral neuropathy including chemotherapy-induced neuropathy or neuropathy induced by other medications
• active smoking
• language barrier
• pregnancy at time of planned DIEP flap surgery and lactation

XX chromosome patients willing to have autologous breast reconstruction