I assume your existing lymphoedema is in the breast? Outcomes would depend very much on the impact of surgery on the lymphatic system around the breast, I would be wanting the advice of a good breast surgeon and also seeing if an experienced lymphoedema therapist had any relevant experience before making any decision. The last thing you want is to have a mastectomy and simply move the blockage around!! I had a year of a persistent recurrent seroma post mastectomy - no-one's fault but my overproductive body trying to heal. General wisdom is that my lymphoedema is not connected, but I'm not 100% convinced