Breast cancer-related lymphedema is one of the most common and feared consequences of breast cancer treatment. Currently, lymphedema is primarily addressed conservatively with compression garments. Regenerative medicine may provide a new treatment option for lymphedema. This Phase 3 trial will examine the efficacy, effectiveness and safety of freshly isolated adipose-derived stromal cells administered in conjunction with a fat grafting procedure to the affected axillary region.

Inclusion Criteria:

• Unilateral arm lymphedema secondary to breast cancer treatment including lymph node dissection.
• Cancer free for at least 1 year
• The patient understands the nature and purpose of this study and the study procedures and has signed informed consent.
• The opposite upper extremity is healthy (no lymphedema).
• ASA score of 1 or 2.
• The patient is able to read, understand, and complete Danish questionnaires.
• Pitting lymphedema ISL grade 1 or 2.
• A minimum circumference difference of 2cm or a minimum volume difference of 200mL.

Exclusion Criteria:

• Pregnant or lactating.
• Bilateral lymphedema
• Current or previous malignancies other than breast cancer.
• Insulin-dependent diabetes.
• Diagnosed with any form of psychotic disorder, which may impact study participation.
• Not ceased smoking during treatment.
• Active implantables (e.g. pacemaker or neurostimulator)
• Unrealistic treatment expectations.
• Known hepatitis, HIV or syphilis infection.

All patients undergo the same liposuction procedure. During general anesthesia, patients are randomized to either fat grafting or sham grafting with saline injection to the axilla. After stem cell suspension, patients receive either stem cell or saline injection depending on randomization using masked syringes.

Participants are blinded, care providers postoperatively are blinded, primary investigator is blinded and all outcome assessors are blinded. The surgeon performing the liposuction and the stem-cell staff are unblinded.