Quantitative Evaluation of Abscopal Effect Based on Biological Effective Dose in Breast Cancer Tumors in Mice Publisher



Zarei H¹ ; Mozdarani H² ; Mahmoudzadeh A³ ; Salimi M⁴ ; Eyni H⁵ ; Bakhshandeh M¹
Source: International Journal of Radiation Research Published:2018

Abstract

Background: Due to abscopal effect, cell damage may occur outside of the radiaon field and the quanficaon of this effect is one of the most challenging debates in radiaon therapy. The aim of this study was to esmate the abscopal effect induced in non-irradiated tumors quantavely by means of biological effecve dose (BED). Materials and Methods: Breast tumors using 4T1 and MC4-L2 cells, were induced into the flank region of Balb/c mice. When palpable, the tumor on one side of the body was irradiated with dose of 28Gy in 14 fracons and 2 Gy per fracon, 5 fracons per week. The tumor on the other side of the body was shielded with a lead plate. BED was esmated based on tumor volume. H&E staining and TUNEL assay were performed to assess histological changes and apoptosis in irradiated and non-irradiated tumors. Results: The effect of radiaon on non-irradiated tumors was more than that on irradiated ones. The BED was 4.49 and 6.74 in 4T1 and MC4-L2 tumors, respecvely. The rao of the tumor volume in the last fracon to that in the first fracon for irradiated 4T1 tumors was 2.32 and in non-irradiated was 1.50. This rao in irradiated and non- irradiated MC4-L2 tumors was 2.64 and 1.98, respecvely. The number of apoptoc cells was higher in non-irradiated ssues. Conclusion: Results indicate that the occurrence of abscopal effect is highly depends on the type of tumor. By means of the abscopal effect, more radiaon dose can be delivered to the tumor and metastac sites.