Comparison of optimal parameters of electromagnetic impulse of electrochemotherapy for treatment of S-180 sarcomas

Baoyi WANG; Hong ZHANG; Zishu WANG; Baoqiang XU

ABSTRACT

BACKGROUND:

Electrochemotherapy(ECT) is a new and an efficient approach for the treatment of tumor. The technique is very easy to control and operate and is of little harm to normal tissue. Especially, it is very efficient in curing the superficial tumors. In the treatment process of ECT, the selection and constitute of electromagnetic impulse are the key factors.

OBJECTIVE:

To use the ECT as a therapeutic method for S-180 sarcomas in Kunming mice and obtain the optimal parameters of electromagnetic impulse in curing.

SETTING:

Department of Wireless Physics, College of Electronics-Information, Sichuan University

DESIGN:

Random grouping design and controlled experiment study MATERIALS This experiment was conducted at the Laboratory of Cells, College of Life Sciences, Sichuan University from January 2003 to May 2004. Totally 106 Kunming mice were randomly divided into 12 groups voltage 500 V, pulse number 5 and capacitance 6,10 and 14 μF, respectively in 3 groups, with 9 mice in each group;voltage 700 V, pulse number 5 and capacitance 6,10 and 14 μF, respectively in 3 groups, with 9 mice in each group; voltage 900 V, pulse number 5 and capacitance 6,10 and 14 μF, respectively in 3 groups,with 9 mice in each group; voltage 700 V, capacitance 10 μF, pulse number 7 and and 9 respectively in 2 groups , with 8 mice in each group , and control group with 9 mice in it.

METHODS:

The treatment includes injection of Bleomycin 0.04 mg per one (intraperitoneal injecting into tumors through multiple points), followed by application of electromagnetic impulse using the needles. The treatment was taken every three days andthree times in total. Mice were euthanized 18 days later. Tumor volume was measured before irradiation and 10 and 18 days after irradiation. Tumor volume (mm3)=3.141 59×length×width×height/6. Inhibitory rate(%)=(average tumor volume of the control group-average tumor volume after irradiation)/average tumor volume of control group×100%. The relative growth velocity=tumor volume after irradiation/Tumor volume before irradiation.MAIN OUTCOME

MEASURES:

Tumor volume; inhibitory rate; relative growth velocity

RESULTS:

Totally 106 animals were enrolled in the experiment and all of them entered the stage of result analysis. ①When the capacitance was 6 μF, the impulse numbers are 5, the voltage altered [for example the 10th day, when voltage was 500, 700, 900 V, the tumor volume was (66.99±91.17),(62.58±71.83),(78.43±73.91) mm3 , respectively]. The effect was the best when the voltage was 700 V, and was the worst when 900 V).②When the voltage and capacitance were fixed and the pulse numbers altered, for example voltage 700 V and capacitance 10 μF, taking the 10th day as the example , the pulse number was 5, 7 and 9, the tumor volume was (80.66±38.17),(41.33±36.40),(39.86±23.03) mm3, respectively. The inhibitory effect was better with the increase of pulse number, and the best when the pulse number was 9.

CONCLUSION:

According to experimental results, following parameters of electromagnetic impulse, can be concluded ①The inhibitory effect is the best when the number of impulse is 5, voltage 700 V, capacitance 6 μF. ②The inhibitory effect increases with the increase of pulse number when the voltage is 700 V and capacitance is 10 μF, and is the best when the pulse number is 9.