Abstract:Objective To explore the effects of bevacizumab on the prognosis and survival of patients with stage Ⅳ colorectal cancer. Methods Sixty-seven patients with stage Ⅳ colorectal cancer admitted to Luzhong Hospital from May 2018 to June 2019 were selected and randomly divided into experimental group (n=33) and control group (n=34).Bevacizumab combined with gimeracil/oteracil/tegafur(S-1) was used in experimental group,and S-1 alone was given in control group.The clinical efficacy,tumor markers,immune indexes,side effects and survival rate were compared between two groups after 2 cycles of chemotherapy.Results After chemotherapy,the total effective rate in experimental group was significantly higher than that in control group (87.88% vs 67.65%,χ2=3.945,P<0.05）.The levels of carcinoembryonic antigen (CEA),carbohydrate antigen （CA）125 and CA199,vascular endothelial growth factor (VEGF),matrix metalloproteinase 2 (MMP2) and MMP9 were significantly lower than those before treatment in both groups and were significantly lower in experimental group than those in control group (P<0.05).There was no significant difference in the incidences of nausea and vomiting,hand foot syndrome,leucopenia,liver and kidney dysfunction(P>0.05）and in the metastasis rate of colorectal cancer (42.42% vs 55.88%, χ2=1.214,P>0.05) between two groups.The 1-year survival rate in experimental group was significantly higher than that in control group (66.67% vs 41.18%,χ2=4.377,P<0.05).Conclusion Bevacizumab combined with S-1 could increase the clinical efficacy,reduce the levels of tumor markers,serum VEGF,MMP2 and MMP9 and improve the prognosis of patients with stage Ⅳ colorectal cancer.