Therapy-refractory lymphatic fistulas following complete lymph node dissection in malignant melanoma: local radiotherapy as an effective therapeutic modality to avoid cancer treatment delay

PURPOSE: Complete lymph node dissection (CLND) for stage III malignant melanoma is associated with substantial morbidity, particularly lymphatic fistulas (LF), which may delay adjuvant therapy. Grade C LF, characterized by prolonged secretion and clinical complications, lacks a standardized treatment algorithm. This study evaluated the efficacy and safety of radiotherapy in managing Grade C LF after axillary or inguinal CLND in malignant melanoma. MATERIALS AND METHODS: We conducted a retrospective, single-center study of patients with stage III malignant melanoma who developed Grade C LF after axillary or inguinal CLND between 2013 and 2021 at the University Hospital Bonn. Radiotherapy was administered as either low-dose or high-dose protocols. Treatment success was defined as LF resolution within 30 days post-radiation. Toxicities were assessed using RTOG and RTOG/EORTC scores. RESULTS: Among 352 CLND procedures, 32 patients (9.1%) developed Grade C LF. Radiotherapy achieved resolution in 84.4% (27/32) of cases, independent site (inguinal vs. axillary, p = 0.999), laterality (p = 1.000), or timing of radiation initiation (p = 0.518). Low- and high-dose protocols achieved comparable success rates (89.5% vs. 76.9%, p = 0.347). However, high-dose radiotherapy caused significantly more acute (46.2% vs. 10.5%, p = 0.038) and long-term toxicities (38.5% vs. 5.3%, p = 0.029). Mean time to therapy success was 27 days after radiation initiation and 64 days after surgery, supporting adherence to the ESMO’s 12 week adjuvant window. CONCLUSION: Grade C LF occurs in approximately 10% of patients following CLND and can delay adjuvant therapy. Radiotherapy, particularly low-dose protocols, is a safe and effective strategy to resolve LF and minimize treatment delays.