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.%背景 腺样囊性癌(ACC)是泪腺上皮性肿瘤中恶性程度最高的一种肿瘤，侵袭性强，复发率和死亡率高。尽管可以采用手术切除、放射治疗和化学治疗等综合性治疗，但疗效仍欠佳。 目的 探讨125 Ⅰ粒子组织间植入对裸鼠移植性ACC的治疗效果，以及粒子放射活度与疗效的关系。方法 在BALB/C裸鼠背部皮下注射0.1 ml ACC-2癌细胞5×10 7个/ml建立荷人ACC裸鼠模型30只。注射后14d选取瘤体体积大致相等的荷瘤鼠25只，用随机数字表法分为5组，每组5只裸鼠。治疗组每只裸鼠分别植入1枚125 Ⅰ粒子，按放射活度分为G1组(0.4 mCi)、G2组(0.6 mCi)、G3组(0.8 mCi)、G4组(1.0 mCi)4个治疗组，G0组(对照组)植入无活性的空心粒子1枚，B型超声扇形扫描对125Ⅰ粒子进行定位监测。每2天测量1次肿瘤直径并计算各组肿瘤体积抑制率，14d后断颈处死裸鼠，制作肿瘤组织标本，行透射电子显微镜及常规病理学染色检测肿瘤坏死凋亡情况并记录肿瘤坏死凋亡边缘距离125 Ⅰ粒子的最大半径。 结果 125 Ⅰ粒子植入14 d，G0组平均瘤体积为( 3713.19±243.23) mm3，G1组、G2组、G3组、G4组分别为(3113.35±316.54)、(2635.85±261.21)、(2538.37±312.16)、( 1686.28 ±231.65 )mm3，与G0组比较，差异均有统计学意义(P＜0.05);G1组、G2组、G3组、G4组的抑瘤率分别为(20.11±3.09)％、(36.18±2.54)％、(40.83±4.17)％、(66.63±5.34)％，即随着125Ⅰ放射活度的增加，抑瘤率明显增高，差异有统计学意义( F=120.240，P=0.000)。125Ⅰ放射活度与抑瘤率呈正相关( r=0.653，P=0.008)。G1组、G2组、G3组、G4组凋亡或坏死距离粒子的最大有效治疗半径依次为(5.2±0.5)、(6.4±0.7)、(7.4±0.4)、(8.2+0.5)mm，差异有统计学意义(F=29.22，P=0.000);125Ⅰ放射活度与最大有效治疗半径呈正相关( r=0.609，P=0.004)。结论125Ⅰ粒子组织间植入对裸鼠移植性ACC持续照射可以抑制肿瘤细胞增生周期，是一种安全、有效、可行、不良反应少的治疗方法。
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