Electrochemotherapy in large and deep-seated soft tissue sarcomas: a pilot study on tumor control, limb preservation, and symptom relief

Electrochemotherapy (ECT) is a locoregional treatment that combines reversible electroporation with chemotherapy to enhance intracellular drug delivery. Clinical evidence for ECT in large, deep-seated, recurrent, or locally advanced soft tissue tumors remains limited. This pilot study primarily evaluated symptom palliation following bleomycin-based ECT, with objective tumor response and treatment-related toxicity assessed as secondary outcomes. Twenty-five patients with recurrent, locally advanced, or metastatic STS tumors resistant to conventional treatments underwent ECT between 2022 and 2025. Bleomycin (15,000 IU/m²) was administered intravenously, followed by electroporation using variable electrode configurations according to tumor characteristics. The primary outcome was symptom palliation. Secondary outcomes included objective tumor response and treatment-related toxicity, while additional clinical outcomes included quality-of-life changes, limb preservation, local progression-free survival (LPFS), and overall survival (OS). The study population had a median tumor size of 87 mm (range 35–320 mm), and 92% of tumors were ≥ 5 cm. Overall symptom palliation was achieved in 16 of 18 symptomatic patients (88.9%), with pain reduction reported in 12 of 14 patients with severe baseline pain (85.7%) and complete cessation of bleeding and tumor-associated discharge in all eight affected patients. EORTC QLQ-C30 scores improved across all evaluated domains, including Global Health, Physical Function, and Role Function, while Pain and Other Symptoms scores decreased significantly (all P < 0.001). ECT enabled conversion to operability in selected unresectable tumors, and long-term limb preservation was achieved in four of the six patients who were initially considered candidates for amputation. An objective response was observed in 21/25 patients (84.0%, 95% CI: 63.9%–95.5%). After a median follow-up of 13.7 months, the 1-year LPFS and OS rates were 56.0% and 76.0%, respectively. The most frequent adverse events were skin reactions and soft tissue necrosis, which were generally manageable with conservative wound care or outpatient debridement. No serious ECT-related systemic adverse events were reported. ECT was associated with symptom palliation, objective tumor response, and manageable treatment-related toxicity in this pilot cohort. These preliminary findings warrant further evaluation in larger prospective controlled studies. Clinical trial registration number : The clinical trial registration code number was (IRCT20190904044697N8, Registration Date: 2022-10-02).