Abstract: Objective The aim of this study was to investigate the relationship between STAT1,STAT3 gene promoter CpG island methylation status and prognosis of patients with colorectal cancer(CRC)and the prognostic factors of CRC patients.Methods The cohort study was conducted to biosamples and follow up 239 patients with primary colorectal cancer pathologically diagnosed in Cancer Hospital of Harbin Medical University(Tumor Hospital).The methylation status of STAT1,STAT3 gene promoter CpG island was analyzed by methylation specific high-resolution melting curve(MS-HRM).Results The survival rates of 239 patients with colorectal cancer at 1 year,3 years and 5 years were 94.90%,86.00% and 67.20%,respectively.The methylation status of STAT1 and STAT3 genes was not associated with postoperative survival in colorectal cancer patients(STAT1:HR=0.85,95% CI:0.55~1.30,P=0.44;STAT3:HR=0.75,95% CI:0.36~1.58,P=0.45).Dukes stage(HR=1.31,95% CI:1.14~1.51,P＜0.01)and intraoperative intestinal stapler use(HR=1.98,95% CI:1.25~3.14,P＜0.01)were important factors affecting the prognosis of colorectal cancer patients.The risk of death in patients with stage D and Dukes was significantly higher than that in stages A and B(HR=1.31,95% CI:1.14~1.51,P＜0.01).Intestinal anastomosis was used during operation.The patient′s prognosis was better than that of patients without an intestinal stapler.However,gender,age,tumor location,gross tumor type,histological classification and postoperative chemotherapy were not associated with the prognosis of colorectal cancer.Conclusion Dukes stage is an independent factor affecting the prognosis of colorectal cancer.The prognosis of patients with intestinal stapler is better than that of non-users.The methylation status of STAT1 and STAT3 in peripheral blood is not a biomarkers for the prognosis of patients with colorectal cancer.

Key words: Colorectal cancer, Methylation, JAK-STAT, Survival analysis