Abstract: Objective The objective of this study was to determine the effect of curative chemotherapy regimen on breast cancer cells and its mechanism.Methods A tumor-bearing mouse model was established and routine dose of capecitabine was given as a conventional chemotherapy group.Continuous low-dose capecitabine chemotherapy was used as a radiotherapy group and no chemotherapy was used as a control group.The expression of microvessel density(MVD),vascular endothelial growth factor(VEGF)and thrombospondin 1(TSP-1)were measured by flow cytometry.The percentage of myeloid-derived suppressor cells(MDSCs),NK cells and macrophages in the program was observed.The tumor size and blood leukocyte count were measured after chemotherapy.Results MVD and VEGF in the radiotherapy group were significantly decreased and TSP-1 was significantly increased in comparison with the conventional chemotherapy group(P＜0.05).The proportion of MDSCs in the radiotherapy group was significantly decreased,the proportion of NK cells and macrophages were significantly increased when compared to the conventional chemotherapy group(P＜0.05).The tumor volume was no difference between the control and chemotherapy groups(P＞0.05).However,the white blood cell count in the radiotherapy group was significantly higher than that in the conventional chemotherapy group(P＜0.05).Conclusion Capecitabine chemotherapy at continuous low-dose inhibits neovascularization and adjusts the proportion of immune cells to suppress tumor formation.Thus,this chemotherapy could reduce side effects caused by chemotherapy and improve the quality of life.

Key words: Metronomic chemotherapise, Antiangiogenesis, Immunological system, Quality of life