Electrochemotherapy achieves high local control of lingual and tonsillar tumors in dogs and cats.

OBJECTIVE: To describe local response, progression-free survival (PFS), and overall survival (OS) in dogs and cats with lingual or tonsillar tumors treated with electrochemotherapy (ECT) alone or combined with surgery. METHODS: Medical records were retrospectively reviewed for dogs and cats with a histologically or cytologically confirmed tumor of the tongue or tonsil treated with ECT alone or combined with surgery, with ≥ 1 posttreatment follow-up. Twenty-nine client-owned animals, 7 dogs and 7 cats with lingual tumors and 15 dogs with tonsillar tumors, were included. Response was assessed by modified Response Evaluation Criteria in Solid Tumors; PFS and OS were estimated by Kaplan-Meier analysis. RESULTS: In dogs with lingual tumors, the objective response rate (ORR) was 85.7% (complete response [CR], 71.4%); the median OS was 270 days, with 2 dogs alive at 980 and 1,090 days, and the median PFS was 263 days. In cats with lingual tumors, the ORR was 71.4% (CR, 57.1%), the median OS was 240 days, and all cats died, most of local progression; the median PFS was 215 days. In dogs with tonsillar tumors, the ORR was 80.0% (CR, 66.7%), the median OS was 240 days, and all dogs died, predominantly of pulmonary metastasis; the median PFS was 210 days. CONCLUSIONS: ECT can provide high local response rates in dogs and cats with lingual tumors. In dogs with tonsilar tumors, even when high local response rates are achieved, patients die predominantly from distant metastasis, warranting a multimodal treatment aproach. CLINICAL RELEVANCE: ECT achieved high local response rates in all groups. It appears most useful for function-preserving treatment for lingual tumors. The combination with surgery allows treatment of larger tumors than ECT alone. The survival of dogs with tonsillar tumors was limited by metastatic dissemination, supporting a multimodal approach.