RESUMEN
Objective To explore the in vivo killing effects of nanosecond pulsed electric fields on mouse breast cancer in tumor bearing BALB/c mice. Methods Twenty four BALB/c mice models with subcutaneous EMT-6 breast cancer were prepared and divided into experimental group and control group (n=12). In experimental group, the mice were treated by the pulsed electric fields with peak voltage of 700 V/cm, rise times of 57 ns, durations of 70μs and duty ratio of 50%on the tumor tissue with two parallel electrodes under anaesthesia. One hundred pulses were given and the energy was just 9.75 J with effective action period of 7 ms. Tumor volume, animal weight and histopathologic changes after 1, 3, 5 and 7 d were observed after irreversible electroporation. Results The tumor volume in experimental group increased more slowly than that in control group, especially at the 1-3 d after treatment with a standstill. Histopathological examination results showed that the tumor tissue had obvious coagulation necrosis and tissue edema after electrical stimulation treatment, and mass vacuole like structure appeared in tumor tissue from the third day after treatment and vascular injury occurred at the early stage. Conclusions In the given field conditions, steep pulsed electric field has inhibitory effect on tumor growth. In order to achieve more ideal tumor therapy effect, further studies on steep pulse dose are needed.