Biphasic pulses enhance bleomycin efficacy in a spontaneous canine perianal tumors model

Perianal tumors (adenoma and carcinoma of the hepatoid glands) are frequently reported in veterinary literature. They are locally aggressive tumors with a low tendency to metastatic spread. An hormonal ethiology has been identified for the development of perianal adenomas in male dogs, while the carcinomas are free from hormonal influence. Standard treatments include surgery, cryotherapy or, in selected cases, radiation therapy. In this article we describe the outcome of a small cohort of canine patients with perianal tumors treated with bleomycin selectively driven by trains of biphasic pulses (electrochemotherapy). Twelve canine patients, eight with adenoma and four with carcinoma of the perianal glands, entered the study and received two sessions of ECT under sedation. The pets had local injection ofbleomycin at the concentration of 1.5 mg/mg and five minutes after the chemotherapy, trains of 8 biphasic electric pulses lasting 50 + 50 micros each, with 1 ms interpulse intervals, were delivered by means of modified caliper and needle array electrodes or, for difficult districts, through paired needle electrode. The overall response rate was 91% with a 83% of complete response (10/12); one dog had a PR that lasted 12 months and another had progressive disease. Electrochemotherapy appears as a safe and efficacious modality for the treatment of perianal tumors and warrants further investigations.