Surgery and Adjuvant Electrochemotherapy Compared to Surgery Alone for Treatment of Canine Incompletely Excised Soft Tissue Sarcomas

The predominant challenge in canine soft tissue sarcomas (STSs) is achieving local tumour control, for which surgical excision remains the standard treatment. When complete margins are not attainable, adjuvant therapy may be recommended. Electrochemotherapy (ECT) combines cytotoxic drugs with electric pulses to enhance drug uptake and antitumour efficacy and has shown promising results. However, its role in incompletely excised STSs remains unclear, with limited control-group studies to confirm its efficacy. This retrospective study compared recurrence rate and time to recurrence (TTR) between dogs with incompletely excised cutaneous or subcutaneous low and intermediate-grade STSs treated with surgery alone or with adjuvant ECT and assessed ECT-related toxicity. Medical records from one oncology centre were reviewed. Dogs were included if completely staged, non-metastatic, and had a minimum follow-up of 10 months. The ECT protocol consisted of two sessions, 2 weeks apart, with intravenous bleomycin followed by biphasic pulses using plate electrodes. Forty-three dogs met the inclusion criteria: 22 underwent surgery alone, and 21 surgery followed by adjuvant ECT. Recurrence occurred in 68.2% and 33.3% of cases, respectively. Kaplan-Meier analysis showed a significantly longer TTR in the ECT group (median not reached vs. 534 days; p = 0.044). Treatment was well tolerated, with mild transient local inflammation in 38% of dogs. These findings support ECT as a safe and promising adjuvant therapy for improving local tumour control in incompletely excised canine STSs.