Axillary Versus Primary Breast Approach for Second-stage Breast Reconstruction

The goal of this clinical trial is to compare the safety of axillary or primary breast approach for second-stage operation in expander-implant breast reconstruction for breast cancer patients. The main question it aims to answer are: 1. if the wound related events, including wound dehiscence, infection, delayed healing is significant less often in patients receiving second stage operation via axillary approach compared with primary breast approach; 2. if the aesthetic outcome is comparable between patients receiving different approach for second stage operation. To answer these questions, the breast cancer patients have received nipple-sparing or skin-sparing mastectomy and had breast tissue expander insertion via breast incision, will be prospectively recruited, and randomized into two groups while receiving implant exchange operation: (1) operate via axillary incision; (2) operate via primary breast incision.