低剂量X射线对荷瘤小鼠局部大剂量照射抑瘤作用的影响

Influence of low dose X-rays on tumor-suppressive effect by local high dose irradiation in tumor-bearing mice

目的：探讨低剂量全身照射对局部肿瘤大剂量照射抑癌作用的影响。方法：采用昆明系小鼠皮下接种S180腹水肉瘤细胞为实验肿瘤模型；荷瘤小鼠局部10Gy或2．5Gy×4次X射线照射前12h或24h接受50，75，100和150mGy全身照射，观察局部照后21d的肿瘤生长百分数。结果：50，75和100mGy全身照射可明显增强局部肿瘤大剂量照射的抑瘤效果；局部照前12h比24h接受低剂量照射的增强效应更明显；局部肿瘤分割剂量照射比单次大剂量照射前的低剂量全身照射的增强效应更显著。结论：低剂量全身照射可增强局部肿瘤大剂量照射的抑癌作用，其增强效应的基本规律可能具有临床意义。

Objective:To study the influence of low dose radiation (LDR) on tumor-suppressive effect bylocal high dose irradiation (LHDI). Methods:Kunming mice implanted subcutaneously tvith S 180 Ascites Sarcoma cells were used as an experimental tumor muodel. The tumor-bearing mice were exposed to whole they irradiation (WBI) with doses of 50, 75, 100 and 150 mGy X-rays 12 h or 24 h before LHDI with doses of 10 Gy or2. 5 Gy × 4 and the tumor growth rate was observed. Results:The tumor-suppressive effect by LHDI was sighficantly enhanced by WBI with 50, 75 and 100 mGy compared with that of LDHI only. The enhanced effect ofLDR given 12 h before LHDI was more marked than that of 24 h before LHDI. The enhanced effect of LDR be-fore LHDI with a fractionation dose of 2. 5 Gy × 4 was more notable than that of single dose of 10 Gy. Conclusion: It was demonstrated that LDR might enhance the tumor-suppressive effect of LHDI. The basic rules of thisenhanced effect might have same significance in clinical therapy.