Where does subcutaneous lymph from the chest wall flow into after mastectomy?

Area of Science:

• Oncology
• Surgical Oncology
• Lymphedema Research

Background:

• Lymphatic flow changes post-mastectomy and axillary surgery are not fully understood.
• Investigating chest wall lymphatic drainage is crucial for managing lymphedema and cancer spread.
• Mastectomy, sentinel lymph node biopsy (SLNB), and axillary lymph node dissection (Ax) can alter lymphatic pathways.

Purpose of the Study:

• To investigate the impact of axillary surgery on chest wall lymphatic flow after mastectomy.
• To compare lymphatic drainage patterns following SLNB omission, SLNB, Ax, and Ax with vascularized lymph node transfer (VLNT).
• To assess lymph flow dynamics in deep epigastric artery perforator (DIEP) flaps used for breast reconstruction.

Main Methods:

• Cross-sectional study involving 100 breasts post-mastectomy.
• Indocyanine green (ICG) lymphography used to visualize chest wall lymph flow directions.
• Comparison of lymph flow patterns across four groups: SLNB omission, SLNB, Ax, and Ax + VLNT.

Main Results:

• Ipsilateral axillary lymph flow was more frequent after SLNB compared to Ax (48% vs. 12.5%, p=0.005).
• No significant difference in contralateral axillary route adoption between SLNB and Ax groups (8% vs. 15%, p=0.65).
• VLNT did not significantly increase ipsilateral axillary lymph flow compared to Ax alone (12.5% vs. 12.5%, p=1.00). Lymph flow in DIEP flaps followed anatomical lymphatic pathways.

Conclusions:

• ICG lymphography is a valuable tool for visualizing post-mastectomy chest wall lymph flow.
• Understanding lymph flow direction aids in predicting cancer metastasis, including lymphoma spread.
• Findings can inform strategies for lymph flow restoration and lymphedema management.