Introduction
Electrochemotherapy is an antitumor therapy that utilizes locally delivered short intense direct current electric pulse to the tumour nodule and chemotherapy. The aim of the present study was to evaluate the electrochemotherapy treatment of perianal tumours of different sizes in dogs.
Material and methods
Between March 2000 and July 2003, 12 patients with all together 26 measurable cutaneous were included in the study. Before treatment, the dogs were sedated. Electrochemotherapy consisted of intratumoral administration of cisplatin at a dose of approx. 1 mg/cm3 tumour volume, followed by application of electric pulses to the tumour. If the treatment with cisplatin as the first chemotherapeutic drug was not successful, electrochemotherapy with bleomycin was performed, with bleomycin at a dose of approx. 3 mg/1 cm3 tumour volume. Square wave electric pulses of 100 μsec, 910 V amplitude (amplitude to electrode distance ratio 1300 V/cm), frequency 1 Hz were delivered through two parallel stainless steel electrodes (thickness 1mm; width 7mm, length 8mm, with rounded tips and an inner distance between them 7 mm) with an electroporator Jouan GHT 1287. Each run of electric pulses was delivered in two trains of four pulses, with 1s interval, in two perpendicular directions. The interval between cisplatin or bleomycin administration and the application of electric pulses was 1-2 min. The treatment response was evaluated according to WHO classification (complete response (CR); partial response (PR); no change (NC) and progressive disease (PD)). The number of objective responses (OR) was determined by combining the number of CR and PR.
Results
Responses to treatment were assessed 4 weeks after the therapy, 82% of all tumors treated with electrochemotherapy responded with objective response (OR) (complete response (CR) = 41%, partial response (PR) = 41%), 16% responded with no change (NC) and one tumor (2%) went in progressive disease (PD). At the end of observation period for each tumor ranging from 1 to 34 months, 92% of OR (CR=65%, PR=27%), 8% of NC and no PD were obtained. To achieve above-mentioned results, average number of electrochemotherapy sessions was 1.6 and in range from 1 to maximum 4 sessions per patient. There were no major local or general side effects noted.
Conclusions
This study shows that electrochemotherapy with cisplatin or bleomycin is an effective treatment of perianal tumours in dogs. The advantages of this therapy are it's simplicity, short duration of treatment sessions, low chemotherapeutic doses, and insignificant side effects, as well as the fact that it can be performed on outpatient basis.