Abstract: Objective To explore the relationship between the expression levels of serum long chain non coding RNA Kinectin 1 antisense RNA 1 (LncRNA KTN1-AS1) and retinoblastoma binding protein 4 (RBBP4) with postoperative recurrence and metastasis in esophageal cancer patients.Methods From May 2018 to May 2021,119 patients with esophageal cancer who underwent surgical treatment in our hospital were included as the study group.They were separated into an occurrence group (n=51) and a non occurrence group (n=68) based on whether there was recurrence or metastasis during a 3-year follow-up.Additionally,100 patients with benign esophageal tumors treated at the same stage were selected as the control group.ELISA method was applied to detect the expression levels of serum LncRNA KTN1-AS1 and RBBP4.Multivariate Logistic regression was applied to analyze the influencing factors of postoperative recurrence and metastasis in esophageal cancer patients.ROC curve was applied to analyze the predictive value of serum LncRNA KTN1-AS1 and RBBP4 for postoperative recurrence and metastasis in esophageal cancer patients.Results The expression levels of serum LncRNA KTN1-AS1 and RBBP4 in the study group were obviously higher than those in the control group (P<0.05).The expression levels of serum LncRNA KTN1-AS1 and RBBP4,and the proportions of mucosal/submucosal infiltration depth,and low differentiation degree and proportion of lymph node metastasis in the occurrence group were obviously higher than those in the non occurrence group (P<0.05).Serum LncRNA KTN1-AS1,RBBP4,proportion of lymph node metastasis,degree of differentiation,and depth of infiltration were influencing factors for postoperative recurrence and metastasis in esophageal cancer patients (P<0.05).The area under the curve (AUC) of the combined prediction of serum LncRNA KTN1 AS1 and RBBP4 for postoperative recurrence and metastasis in esophageal cancer patients was 0.912,which was better than their individual predictions (Z_{combination-LncRNA} KTN1 AS1=2.470,Z_{combination-RBBP4}=1.994,P=0.014,P=0.046),the sensitivity and specificity of the combined prediction were 90.20% and 85.29%,respectively.Conclusion The expression levels of serum LncRNA KTN1-AS1 and RBBP4 in esophageal cancer patients are obviously increased,which is closely related to postoperative recurrence and metastasis.The combined detection of the two has good predictive value for postoperative recurrence and metastasis in patients.

Key words: esophageal cancer, long chain non coding RNA Kinectin 1 antisense RNA 1, retinoblastoma binding protein 4, recurrence, metastasis