[Anticancer efficacy of combining cytosine deaminase/5-fluorocytosine gene therapy and radiotherapy on cervical carcinoma].

OBJECTIVE: To observe the effect of combining cytosine deaminase (CD)/5-fluorocytosine (5-FC) gene therapy with radiotherapy on cervical carcinoma in nude mice, and to explore if there is a synergistic effect between the two therapies. METHODS: HeLa cells were injected into the 24 female nude mice who were 6-8 weeks old. When the tumors grew to 4.0-7.0 mm in diameter, the mice were divided into 4 groups randomly: control group, CD/5-FC gene therapy group, CD/5-FC gene therapy plus radiotherapy group, radiotherapy group. The volumes and inhibiting rates of the tumors were calculated. RESULTS: (1) The tumor volumes in CD/5-FC gene therapy group (728 +/- 201) mm(3), CD/5-FC gene therapy plus radiotherapy group (357 +/- 113) mm(3), radiotherapy group (739 +/- 419) mm(3), were smaller compared with that in the control group (1168 +/- 380) mm(3), the difference was significant (P < 0.05); tumor volumes in CD/5-FC gene therapy plus radiotherapy group was significantly smaller compared with that in the CD/5-FC gene therapy group and radiotherapy group (P < 0.05). (2) The tumor-inhibiting rate of the radiotherapy group was 36.74%, of the CD/5-FC gene therapy group was 37.66%, and of the CD/5-FC gene therapy plus radiotherapy group was 69.45%, the latter being significantly higher than that of the former two groups (P < 0.05). (3) There was a synergistic effect between CD/5-FC gene therapy and radiotherapy. CONCLUSIONS: There is a synergistic effect between CD/5-FC gene therapy and radiotherapy. CD/5-FC gene therapy combined with radiotherapy may be a good supplementary method for cancer synthetic treatment.