Kidney and liver histology in tumour-induced rats exposed to non-contact electric fields

Background: There were an estimated 2.1 million breast cancer diagnoses in 2018 worldwide, which is about 11.6 of the total cancer incidence. A novel modality of cancer treatment based on exposure to non-contact electric fields has been developed to reduce cancer incidence. However, the safety of the electric field exposure was not fully investigated. Therefore, the purpose of this study is to observe the safety of the electric field exposure on renal and liver structure. Methods: Female Sprague-Dawley rats were divided into one control group and three treatment groups. Animals were treated with 7,12-dimethylbenzaanthracene for mammary tumour induction and exposed to non-contact electric fields individually for 10 hours a day for three weeks. Fresh samples of the kidney and liver were collected for observing structural damage in both organs. The two organs were prepared for histopathological cross-sectioning using the paraffin method and Hematoxylin & Eosin staining followed by histological scoring using the post-examination masking method. Results: The damages found in the kidney were the following: thickening of Bowman capsule, karyolysis, karyorrexhis, pyknosis, cloudy swelling, epithelial sloughing, inflammation, haemorrhage, and congestion. The number of inflammation and haemorrhage in the kidney structure of the placebo group was the lowest and significantly different from the three other groups. All damages in the kidney were also found in the liver, but each showed different levels of damage. The damages in the kidney and liver caused by the exposure were not significant. Conclusions: The non-contact electric fields were not harmful to renal and liver structure in tumour-induced rats. Instead, it may increase the renal function in normal rats.