Clinical effectiveness and safety of domestic 125I plaque irradiation for experimental choroidal melanoma / 中华实验眼科杂志

ABSTRACT

Background Choroidal melanoma (CM)is the most common primary intraocular tumor,and brachytherapy is one of the most common therapeutic modality in the treatment of the tumor.However,this irradiation approach has not been evaluated in China. Objective The present study was to analyze the effectiveness and safety of domestic 125I plaque irradiation in the treatment of CM. Methods Forty New Zealand albino rabbits were randomized into 5 groups with 8 rabbits 8 eyes (right eyes) in each group.CM models were established in 16 of 40 New Zealand albino rabbits by implanting the rat B16F10 melanoma cell fragments into the suprachoroidal space of right eyes.After 3 weeks,domestic 125I plaque was fixed at the location of CM in the irradiation group 1,and 8 rabbits with CM served as model control group.The clinical effectiveness of 125I plaque for CM was evaluated based on the fundus examination with indirect ophthalmoscopy,B scan ultrasonography,fundus photographs and color Dopplerimaging.Regarding the safety study,domestic 125I plaque was fixed on the normal right cycs of normal rabbits,while the plaques without 125I seeds were used as the sham group.No intervene was performed in the rabbits of blank group.The number of CD4+,CD8+ T cells in peripheral blood was detected by flow cytometry before plaques implanted and on 3,7,15 and 30 days after the plaque was removed.The animals were sacrificed and the eyes were obtained for histology examination.The use of the experimental animals complied with Statement of ARVO. Results After implantation of B16F10 melanoma cell fragments,CM grew steadily and rapidly with the similar size between irradiation group 1 and model control group ( P =0.550).One week after administration of the treatment,tumor size was(0.31±0.07 )cm in irradiation group 1 and (0.85±0.18 )em in the model control group,with the significant difference between them( P=0.001 ).Two week after application of 125I plaque,the size of tumor was smaller than that before irradiation (P=0.007 ).Histologically,the tumors were mostly limited beneath the pigment epithelial layer with less neovascularization,fibrosis in the tumor was found in some area in the irradiation group when compared with model control group.No significant differences were found in the proportions of CD4+,CD8+ T cells and CD4+/CD8+ at different time points in the irradiation groups of normal eyes and sham group (Fgroup =0.770,8.110,2.230; P=0.380,0.060,0.140; Ftime =0.770,3.220,4.230; P =0.550,0.170,0.004 ).Chronic inflammatory cells infiltration cornea,subconjunctival epithelial and selera surface,but sclera had no necrosis and organization.Conclusions These results suggest that domestic 125I plaque irradiation is effective for the treatment of CM,and has limited side effects on normal rabbits.