^125I粒子组织间植入联合外照射治疗小鼠Lewis肺癌的实验研究

目的探讨^125I粒子组织间植入联合外照射治疗肺癌的有效性。方法建立C57BL／6小鼠Lewis肺癌（LLC）实体瘤模型后，按完全随机化法分为对照组、单纯^125I粒子组织间植入内放疗组、单纯外放疗组（15Gy）、^125I粒子组织问植入联合外放疗（^125I＋外放疗8Gy）组，每组6只小鼠。分组处理后每3天测量肿瘤体积，15d后处死小鼠并测肿瘤质量，计算抑瘤率，制作肿瘤组织标本，行常规病理学检查，以免疫组织化学法检测肿瘤微血管密度（MVD）的表达。利用单因素方差分析比较组间差异，行SNK法q检验。结果与对照组比较，单纯内放疗组、单纯外放疗组（15Gy）及联合放疗组（^125I粒子＋外放疗8Gy）LLC体积均有不同程度的生长抑制（q=11．06，17．13，16．31，P均〈0．05），单纯外放疗组与联合放疗组最明显（抑瘤率分别为50．9％、48．4％），虽目前两者瘤质量差异无统计学意义（q=0．50，P〉0．05），但联合放疗组抑瘤率高于单纯内放疗组（48．4％与28．6％）。免疫组织化学结果显示4组小鼠肿瘤MVD值分别为（23．33±4．84）、（17．50±3．67）、（11．83±2．14）、（12．67±3．39）个微血管／高倍视野（×200），单纯内放疗组的MVD值低于对照组，且高于联合放疗组，差异有统计学意义（q=3．92和3．25，P均〈0．05），而联合放疗组与单纯外放疗组间的差异无统计学意义（q=0．57，P〉0．05）。结论放疗可通过降低肿瘤MVD值，减少血管生成而抑制肿瘤生长。在达到相同的肿瘤局部控制率的情况下，联合^125I粒子组织间植入照射可有效减少外照射剂量，使周围正常组织器官的吸收剂量减低。

The experimental study of ~(125)I seeds interstitial brachyherapy combined with extermd beam radio-therapy for Lewis lung cancer in C57BL/6 nice

Objective The purpose of this study was to investigate the efficacy of ~(125)I seeds interstitial brachytherapy combined with external beam radiotherapy for lung neoplasm.Methods Each set of six C57BL/6 mice bearing Lewis tumor was stratified into four groups on day 1:vehicle control, ~(125)I seeds interstitial brachytherapy alone,external beam radiotherapy(15 Gy)alone,and combination of ~(125)I seeds interstitial brachytherapy with external beam radiotherapy(8 Gy).After treatment.the volulne of the tumors was measured every 3 days.The animals were executed,the weight of tumors was measured.tumor control rate was calculated and pathological examination was performed on day 15.The intratumoral micro-vaseular density (MVD)in each group was evaluated by inmmnohistochemical methads.Tumor volume.weight and MVD were compared by one-way ANOVA,student.newlnan-keuls(SNK)-q analysis.Results Comparing with control group,the other three groups had significant inhibiting effect on the growth of lewis tumor(q=11.06,17.13,16.31,all P<0.05).Tumor growth inhibition in external beam radiotherapy alone group and combination group (50.9%and 48.4% respectively)were higher than ~(125)I seeds interstitial brachytherapy group(28.6%).while the difference of tumor weisht was not significant between the former two groups(q=0.50.P>0.05).Immunohistochemistry analysis showed that the MVD value in the four groups wag(23.33±4.84).(17.50±3.67),(11.83±2.14)and(12.67±3.39)/(high power field×200)regpectively.The MVD value of ~(125)I seeds interstitial brachytherapy alone group was much lower than that of control group,and higher than combination group(q=3.92 and 3.25,both P<0.05).Additionally,there was no significant difference between external beam radiotherapy alone group and combination group(q=0.57,P>0.05).Conclusions Radiotherapy can.significantly reduce the MVD values of tumor and inhibit tumor growth through the mechanisms of antiangiogenesis.The combined treatment of lung tumors with implanted ~(125)I seeds and external beam irradiation can decrease the total dose of the external beam irradiation and,hence,offer the possibility of considerable dose sparing of normal tissues without compromising local tumor control rates.