Effects of 125 I seeds interstitial brachytherapy on orbital adenoid cystic carcinoma

Abstract

Background Adenoid cystic carcinoma is a malignant tumor originating from lacrimal gland epithelium with high recurrence rate and mortality because of its invasiveness. Although surgery, radiotherapy and chemotherapy are used clinically,the curative effect is not enough satisfied. Objective This study was to provide an experimental basis for clinical application of 125 Ⅰ seeds interstitial brachytherapy. Methods Human ACC-2 cell links were transplanted subcutaneously in the back of 30 SPF BALB/C nude mice to establish the ACC model,and 25 of these mice with suitable sizes of tumor were selected and randomly divided into the G1 (0. 4 mCi 125 Ⅰ ), G2 (0. 6 mCi 125 Ⅰ ) ,G3(0. 8mCi 125 Ⅰ ) ,and G4( 1.0mCi 125 Ⅰ ) groups according to the different therapeutic radioactivity treatments,with 5 nude mice for each group,and a 125 Ⅰ seed without radioactivity was used in 5 mice as the control group. The dimensions of the tumors were measured at 2-day intervals and the inhibition rates of tumors were calculated. Nude mice were killed 14 days later by the broken neck method,and the amount of apoptosis and necrosis as well as the maximum effective radius of tumor to 125Ⅰ seed were detected under the transmission electron microscope and routine pathological examination. Results Fourteen day after operation, the dimension of tumors was (3713.19±243.23)mm3 in the G0 group;while in the G1 ,G2 ,G3 and G4 groups,the dimensions of tumors were (3113.35±316.54) mm3,(2635.85±261.21) mm3, (2538.37±312.16) mm3 and(1686.28±231.65) mm3,respectively, showing a significant decrease in comparison with the Go group( P＜0. 05 ). The tumor inhibitory rates in the G1 ,G2,G3 and G4 group were(20. 11±3.09)％, (36. 18±2.54)％ ,(40. 83±4. 17)％ ,and(66. 63±5.34)％ ,with an obvious elevation with the increase in the dose of 125 Ⅰ ( F=120. 240,P=0. 000). Correlative analysis showed that the intensity of radioactivity from 125Ⅰ had a positive correlation with tumor inhibitory rate (r =0. 653,P =0. 008 ). The maximum effective radius were ( 5.2 ±0.5 ) mm, ( 6.4 ±0. 7 ) mm, ( 7.4 ±0.4 ) mm, and ( 8.2 ±0. 5 ) mm in the G1 ,G2, G3 and G4 groups, with the considerable differences among them (F=29. 22, P=0. 000). Radioactivity of 125 Ⅰ exhibited positive correlation with the maximum effective radius ( r =0. 609, P =0. 004). Conclusions 125 Ⅰseed implantation brachytherapy can inhibit the growth of the transplanted ACC in BALB/C nude mice by suppressing the proliferation of tumor cells. It is a safe ,feasible and effective method to treat adenoid cystic carcinoma. Key words: 125 Ⅰ seeds; Adenoid cystic carcinoma; Brachytherapy