A Video Protocol of a Randomized Controlled Clinical Trial - Electrochemotherapy of Cutaneous Metastases with Reduced Dose Bleomycin (BLESS Trial).

Cutaneous metastases in patients with incurable cancer represent a significant problem as they often cause pain, discomfort, and emotional distress that affect everyday life. Finding treatment options that are both effective and gentle is essential. ECT offers one such possibility. Here, short, high-voltage electrical pulses are applied directly to the tumor, briefly opening tumor cells, allowing chemotherapy to enter more effectively and kill cancer cells. Traditionally, patients receive 15.000 IU/m2 of bleomycin intravenously, but emerging evidence suggests that a lower dose may be just as effective while causing fewer side effects. This protocol describes an ongoing double-blinded, randomized clinical trial that tests whether ECT with half the standard bleomycin dose is non-inferior to the conventional regimen for tumor control in patients with cutaneous metastases. The article outlines randomization and blinding procedures, pretreatment evaluation, bleomycin preparation and administration, electrode placement, pulse delivery, and response evaluation using the modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria. In addition to clinical response at three months, the protocol includes pharmacokinetic blood sampling and qualitative interviews with the patients to enable a comprehensive evaluation of treatment impact. Baseline tumor characteristics from the first 15 enrolled patients and an example of how mRECIST is applied are presented. Critical steps to ensure methodological rigor are discussed, including standardized tumor measurements, consistent electrode positioning, and predefined management of confluent or poorly demarcated tumors. By visually outlining the procedural workflow and key methodological considerations, this article provides a reproducible framework for dose optimization in ECT. It supports future implementation of reduced-dose regimens in clinical oncology practice.