139. The Deltopectoral Lymph Node: A Potential Protective Biomarker for Breast Cancer-related Lymphedema

PURPOSE: The lateral upper arm pathway is theorized as a collateral route of superficial lymphatic drainage protective against breast cancer related lymphedema (BCRL) after axillary lymph node dissection (ALND). This study describes lymph nodes draining the lateral upper arm pathway. METHODS: Healthy female volunteers underwent bilateral ICG lymphography and nuclear lymphoscintigraphy. Nuclear tracer was injected over the cephalic vein in the upper arm. Lymph nodes with tracer uptake were recorded as deltopectoral, Station 1 (Axillary Levels I, II, or III and Interpectoral), or Station 2 (Infraclavicular and Supraclavicular Levels IV or Vb) by a nuclear medicine physician (K.D.). RESULTS: 76 arms of 38 volunteers were included. Drainage to Station 1, Station 2, and neither station was observed in 96% (73/76), 23% (18/76), and 4% (3/76) of arms, respectively. Functional drainage to deltopectoral lymph nodes was observed in 34% (26/76) of arms. No differences were observed between arms with or without deltopectoral lymph nodes draining to Station 1 lymph nodes (92% vs 98%, p = 0.227) or neither station (4% vs 2%, p = 0.633), respectively. A significant difference was observed between arms with or without deltopectoral lymph nodes draining to Station 2 lymph nodes (46% vs 12%, p = 0.0009). CONCLUSION: Deltopectoral lymph node drainage is significantly correlated with Station 2 lymph node drainage, demonstrating the lateral upper arm pathway is a collateral pathway of superficial lymphatic drainage. As Station 2 lymph nodes are preserved in an ALND, deltopectoral lymph node drainage represent an important biomarker for BCRL risk and severity after ALND.