Antitumor Efficiency of Electrochemotherapy By High and Low Frequencies and Repetitive Therapy in the Treatment of Invasive Ductal Carcinoma in Balb/C Mice

objective: in electrochemotherapy (ect), there is an unpleasant sensation of muscle contraction when using a low frequency (1 hz). therefore, by increasing the pulse frequencyabove the tetanicfrequency this painfulsensation can be reduced. theaimof thepresentstudyistocomparethetreatmentefficienciesoflowandhighfrequencyect,andestimatethe effectof its repeated sessions. materials and methods: we transplanted invasive ductal carcinoma into the flanks of female balb/c mice. ect was performed on the mice by the use of 8 pulses, 1000 v/cm, of 100 µs duration at 1 hz and 5 khz repetition frequencies along with intra-tumoralinjectionsofbleomycin.wealsousedthisectprotocolforthesecondtherapysessionsix days after tumour regrowth. theeffectof treatment was measured bycalculatingthe tumor volumes for 24 days following treatment. statistical analysis wasperformedwithanova.results: ect at 1 hz and 5 khz pulse frequencies demonstrated significant inhibition of tumor growth, but after the first treatment the tumours began to regrow. repetitive ect sessions increased the curability of tumors up to 40% in the group treated by 1 hz frequencyand 60% in the group treated with 5 khz frequency.conclusion: our results demonstrate that the effects of 1 hz and 5 khz pulse repetition frequencies are comparable for inhibited tumour growth. repetitive treatment can improve the effectiveness of ect.