Document Type : Original Article
Department of Medical Physics, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Department of Immunology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Objective: The treatment efficiency of electrochemotherapy (ECT) or the use of a chemotherapy agent with a high electric field and low frequency has been reported. Unfortunately this protocol induces an unpleasant sensation to the patient. Therefore, the aim of this study was to investigate the efficiency of combined low electric field and high repetition frequency for the treatment of an animal tumor model, invasive ductal carcinoma.
Materials and Methods: Female Balb/c mice were transplanted with invasive ductal carcinoma. ECT with bleomycin and two different electric pulse simulation protocols were used. In the first protocol, eight high pulses at an amplitude of 1000 V/cm with 100 μs duration and repetition frequencies of both 5 kHz and 1 Hz were delivered. In the second protocol, low pulse amplitude of 100 V/cm with 5 kHz frequency and different numbers of pulses 500 (1 pulse with 50 milliseconds duration), 2000 (4 pulses with 50 milliseconds duration), 4000 (8 pulses with 50 milliseconds duration) and 5000 (10 pulses with 50 millisecond duration) at 100 μs were applied.
Results: ECT with a higher repetition frequency of electric pulses and low voltage inhibits tumor growth and has a comparable effect to the 5 kHz and 1 Hz pulse repetitions at high voltage. Based on the results, the best antitumor effect was obtained at 4000 pulses or higher, with high frequency and low voltage (p<0.05). The rate of inhibition of tumor growth statistically increased with electric pulse numbers higher than 2000.
Conclusion: The finding indicated that ECT with the use of low pulse amplitude and high frequency, combined with the best number of pulses has a comparable effect to a clinical protocol.