The treatment of canine mast cell tumours with electrochemotherapy with or without surgical excision

Abstract

To describe the results of electrochemotherapy (ECT) in dogs with mast cell tumours (MCTs) either as first line therapy or as an adjuvant to surgery. The treatment combines administration of low dose chemotherapeutic drugs with the application of microsecond electric pulses, which cause the temporary permeabilization and increased porosity of the tumour cell membranes. The design of this study is a retrospective case series. A total of 51 dogs with MCTs were included and classified according to ECT procedure into 4 groups (ECT only, 15 cases, intra-surgery ECT, 11, ECT Adjuvant to surgery, 14, Surgery followed by ECT, 11). The four groups (staged with location, size and grade) were evaluated to assess complete or partial remission, disease free interval, overall survival time and local toxicity. In this case series, Boxers, mixed breed and Labrador Retrievers, male dogs, between 4 and 9 years old were more represented. MCTs were predominantly grade 2 (Patnaik) and T stage 0-1, I-1 (World Health Organization). Treated lesions were most commonly identified on the hindlimb and head where curative surgery would involve cosmetic or functional compromise. The intra-surgery group of dogs showed the best disease free interval with Kaplan-Meyer analysis. Local toxicity induced by ECT ranged mostly from 1 to 4 in a 5-point arbitrary scale with 0 - no toxicity to 5 - highest toxicity. In this study, ECT can be applied successfully as an exclusive therapy in smaller MCTs as an alternative to surgery. ECT can be combined with surgery either intra-operatively or post operatively for larger lesions without significant toxicity.

Soft tissue sarcoma in dogs: A treatment review and a novel approach using electrochemotherapy in a case series

“…ECT coupled with intravenous bleomycin was well tolerated without any systemic side effect and locally showing only low toxicity in most cases. Using a previously published scale, we scored local treatment toxicity . Local toxicity was overall well tolerated, with 66.7% of dogs having a toxicity score ≤ 2.…”

“…Local side effects were self‐limiting in all dogs and managed only medically when needed. In the study, about ECT in canine mast cell tumour, Lowe et al recorded 53% of mild local toxicity (score ≤ 2). The difference between this and our result can be explained by the different behaviour of the two tumour histotypes.…”

“…ECT with either bleomycin or cisplatin has been proven safe and effective on many canine neoplasms such as mast cell tumour and perianal tumours and has also been coupled with gene‐electrotransfer with interleukin‐12 in the treatment of canine mast cell tumour . The operating procedure for ECT in dogs and cats has been published recently as a visualized paper …”

“…33,34 Finally, ECT with bleomycin has been recently found to induce evidence of immunogenic cell death in a murine model, suggesting its role in the host immune response against the tumour. 35 ECT with either bleomycin or cisplatin has been proven safe and effective on many canine neoplasms such as mast cell tumour [36][37][38] and perianal tumours 39 and has also been coupled with geneelectrotransfer with interleukin-12 in the treatment of canine mast cell tumour. 40 The operating procedure for ECT in dogs and cats has been published recently as a visualized paper.…”

“…Repeated ECT treatments are a well-established practice in human patients with good results on various tumour histotypes27,28,54 and, although our sample is too small to draw any conclusion, with slowgrowing tumours, such as low-grade canine STSs, multiple ECT treatment can potentially obtain even better results regarding local disease control and DFI.ECT coupled with intravenous bleomycin was well tolerated without any systemic side effect and locally showing only low toxicity in most cases. Using a previously published scale, we scored local treatment toxicity 38. Local toxicity was overall well tolerated, with 66.7% of dogs having a toxicity score ≤ 2.…”