Larger Lymphatic Vessel Caliber During Lymphatic Microsurgical Preventive Healing Approach (LYMPHA) is Associated with Lower Lymphedema Rates

BACKGROUND: The incidence of Breast Cancer Related Lymphedema ranges from 15-40 % after a complete axillary lymph node dissection (ALND) depending on other treatment modalities like chemotherapy, radiation, and the extent of dissection (1). The Lymphatic Microsurgical Preventive Healing Approach (LYMPHA) reduces the risk of lymphedema after ALND (2). We identified surgical factors of LYMPHA that influence lymphedema rates focusing on the lymphatic vessel caliber utilized. METHODS: A single-institution retrospective cohort study included breast cancer patients undergoing ALND and LYMPHA from April 2021 to November 2022 with a follow-up of at least one year. Lymphedema was defined as a Lymphedema Index (L-Dex) (Bioimpedance Spectroscopy) measurement outside the normal range (±10 L-Dex unit) or an increase of ≥10 units from baseline. The primary outcome was the correlation between the L-Dex of patients with a lymphatic caliber of ≤0.6 mm vs >0.6 mm. The secondary outcome was to assess the difference in the L-dex from baseline after a follow-up of one year. RESULTS: 58 patients with documented lymphatic caliber were analyzed. The mean age and BMI were 52.1 years [SD 11.2] and 27.2 [SD 5]kg/m2 respectively. We divided them into two cohorts: patients that had lymphatic caliber ≤0.6 mm 55.2 %(n=32) vs >0.6 mm 44.8%(n=26). The demographic characteristics and cancer stage were equally distributed between both cohorts. Treatment factors like receipt of taxane-based chemotherapy, radiation, number of nodes resected, number of positive nodes, and number of anastomoses that influence lymphedema rates were equally distributed between both cohorts. The median baseline L-Dex in patients with a lymphatic caliber ≤0.6 mm was 2.25 [2.85] and 2.80 [2.69] for lymphatic caliber > 0.6 mm (p=0.76). After one-year follow-up, the L-Dex was 4.20 [7.74] for lymphatic caliber ≤0.6 mm and 1.80 [2.42] for lymphatic caliber >0.6 mm (p=0.006). The L-Dex difference from baseline was higher for lymphatic caliber ≤ 0.6 mm compared to >0.6 mm (3.15 vs 2.65, p=0.02). 6 patients (10%) developed lymphedema, all of whom had a lymphatic caliber ≤0.6 mm. A larger lymphatic caliber was associated with a lower L-Dex at 12 months (p=0.01). It was also associated with a lesser difference from the baseline after one year which was maintained on univariate analysis (p=0.02) and multivariate analysis controlling for radiation, chemotherapy, and number of lymph nodes excised (p=0.04). CONCLUSION: Lymphatic vessel caliber >0.6 mm during LYMPHA with ALND is associated with a lower postoperative L-Dex and less increase from the baseline L-dex score. The present analysis highlights an opportunity for collaboration in a multi-institutional study to improve the standardization of LYMPHA. REFERENCES: 1. DiSipio, T. et al. Incidence of unilateral arm lymphoedema after breast cancer: a systematic review and meta-analysis. Lancet Oncol. 14, 500–515 (2013). 2. Levy, A. S. et al. Lymphatic Microsurgical Preventive Healing Approach for the Primary Prevention of Lymphedema: A 4-Year Follow-Up. Plast. Reconstr. Surg. 151, 413 (2023).