高低氧放疗对小鼠肿瘤及正常组织的效应初探

目的探讨高低氧放疗时间标准的确立及单次照射肿瘤组织和正常组织的效应。材料与方法实验肿瘤为Ｔ７３９纯系小鼠ＬＡ７９５自发性肺腺癌，以生长延缓为观察指标，正常组织用评分法对昆明鼠右后肢的皮肤反应程度作观察指标。实验分为单纯空气组、单纯高氧（碳合氧，９５％Ｏ２＋５％ＣＯ２）组、高低氧组（低氧气体为１０％Ｏ２＋８５％Ｎ２＋５％ＣＯ２）。结果（１）在吸入５分钟高氧后立即改吸低氧，同时照射，直至照射结束后停止吸气，肿瘤效应无明显下降，证明其为高低氧照射的时间标准。（２）单次照射肿瘤效应高低氧组与单纯高氧组接近，增敏比（ＳＥＲ）为１．７９和１．８０。（３）单次照射皮肤反应高低氧组明显低于单纯高氧组，其ＳＥＲ分别为１．３０及２．２０。（４）对皮肤反应来说，高低氧照射的治疗获得系数（ＴＧＦ）为１．３８，而单纯高氧组为０．８２。结论高低氧放疗可明显提高肿瘤组织效应，而对正常组织的损伤较低，可显著提高ＴＧＦ。

Radiosensitization of a murine tumor and normal tissue by carbogen plus low concentration oxygen radiotherapy

Purpose Settling time course of carbogen plus low concentration oxygen radiotherapy (CPLCOR) in single dose radiation response of murine tumor and normal tissue. Materials and Methods The transplantable spontaneous tumor LA795 in inbred T739 mice was used for tumor response study, and the skin reaction of hind foot of Kunmin mice for normal tissue response. Experiments were divided into three groups: air, carbogen (95%O 2 5%CO 2) alone ,and carbogen plus low concentration oxygen (10%O 2 85%N 2 5%CO 2).Tumor growth delay was used as end point for tumor response. The end point of skin radiation response was the Douglas grading method. Results (1) 5 minutes carbogen exposure prior to radiation, then switch to low concentration oxygen exposure till the end of radiation was the time criteria for CPLCOR. (2) Radiosensitization enhancement ratios(SERs) for single dose irradiation on tumor according to CPLCOR group and carbogen alone group were 1.79 and 1.80. (3) SERs for single dose irradiation on skin reaction were 1.30 and 2.20 according to above groups, respectively. (4) In contrast to air group, therapeutic gain factor (TGF)of CPLCOR group was 1.38, carbogen alone group was 0.82.Conclusion CPLCOR which aim to overcome tumor hypoxia and protect normal tissues can enhance TGF with high potential for clinical use.