Electrochemotherapy of skin metastases from malignant melanoma: a PRISMA-compliant systematic review.

The main treatment of MM metastases are systemic therapies, surgery, limb perfusion, and intralesional talimogene laherparepvec. Electrochemotherapy (ECT) is potentially useful also due to the high response rates recorded in cancers of any histology. No randomized studies comparing ECT with other local therapies have been published on this topic. We analyzed the available evidence on efficacy and toxicity of ECT in this setting. PubMed, Scopus, and Cochrane databases were screened for paper about ECT on MM skin metastases. Data about tumor response, mainly in terms of overall response rate (ORR), toxicity (both for ECT alone and in combination with systemic treatments), local control (LC), and overall survival (OS) were collected. The methodological quality was assessed using a 20-item validated quality appraisal tool for case series. Overall, 18 studies were included in our analysis. In studies reporting "per patient" tumor response the pooled complete response (CR) was 35.7% (95%CI 26.0-46.0%), and the pooled ORR was 80.6% (95%CI 68.7-90.1%). Regarding "per lesion" response, the pooled CR was 53.5% (95%CI 42.1-64.7%) and the pooled ORR was 77.0% (95%CI 56.0-92.6%). One-year LC rate was 80%, and 1-year OS was 67-86.2%. Pain (24.2-92.0%) and erythema (16.6-42.0%) were the most frequent toxicities. Two studies reported 29.2% and 41.6% incidence of necrosis. ECT is effective in terms of tumor response and tolerated in patients with skin metastases from MM, albeit with a wide variability of reported results. Therefore, prospective trials in this setting are warranted.