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

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. 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. 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. 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.