Pre-pectoral Tissue Expander and Acellular Dermal Matrix for a Two-stage Muscle Sparing Breast Reconstruction

This study is collecting safety and outcome data on a modern breast reconstruction technique called pre-pectoral (above the muscle) reconstruction using a tissue expander and acellular dermal matrix (ADM — a biological mesh). It is used after mastectomy and avoids the older method of placing the expander under the chest muscle. **You may be eligible if...** - You had a mastectomy (single or double) followed by two-stage reconstruction using a tissue expander placed above the chest muscle (pre-pectoral), with ADM support - You had a preventive (risk-reducing) mastectomy with the same reconstruction approach **You may NOT be eligible if...** - Your expander was placed under the muscle (submuscular) - Your reconstruction used a back muscle flap (latissimus dorsi) or did not use ADM - You had a delayed reconstruction (not at the same time as mastectomy) - You have had prior breast surgery Talk to your doctor to see if this trial is right for you.