The pattern of arm lymphatic drainage and subclinical lymphedema progression after axillary lymph node dissection: a prospective cohort study.

Background: Breast cancer treatment-related lymphedema (BCRL) is a chronic progressive morbidity for which a definitive cure has not yet been achieved. Since axillary lymph node dissection (ALND) is the main risk factor, we have studied the pattern of lymphatic drainage and subclinical lymphedema progression with ICG lymphography (ICG-L) after ALND as a part of our strategy to prevent BCRL.

Methods: This study was a prospective cohort of breast cancer patients who underwent ALND between October 2022 and August 2024. We prospectively evaluated postoperative lymphatic drainage with ICG-L. Subclinical lymphedema progression to lymphedema was analyzed using the Kaplan-Meier method.

Results: Sixty-three patients were analyzed. Five classifications of lymphatic pathways were identified. The most prevalent pattern was arm and chest wall dermal backflow (DB), draining to internal mammary nodes or type III in 54% of cases, followed by arm DB and collateral drainage to clavicular nodes (type II) in 19.1%, and arm DB only (type I) in 14.3% cases. The cumulative incidence of subclinical lymphedema progression to BCRL was 71.7% (95% CI, 47.0-96.4) with a median BCRL incidence of 13.8 months (95% CI, 10.0-17.5). The hazard rate of BCRL reached its peak at 3 and 12 months.

Conclusion: The lymphatic drainage pattern of the arm will mainly drain into the internal mammary and clavicular nodes after ALND. A substantial number of subclinical cases progressing to early-stage BCRL can be detected by ICG-L within the first year. This finding could be used to develop strategies for BCRL prevention.