Abstract: Objective To explore the clinical value of microsatellite instability(MSI) combined with tumor mutation load(TMB) in evaluating postoperative recurrence and metastasis in patients with non-small cell lung cancer(NSCLC).Methods A retrospective selection was performed on the 80 patients with NSCLC undergoing radical surgery in the hospital between March 2020 and March 2021.All underwent maintenance therapy after surgery.According to presence or absence of recurrence and metastasis at 1 year after surgery,they were divided into recurrence-metastasis group (47 cases) and non-recurrence-metastasis group (33 cases).The clinical data in both groups were collected.MSI and TMB detection of pathological tissues were conducted.The value of MSI and TMB in predicting recurrenceand metastasis of NSCLC patients after surgery was analyzed and compared.Results The univariate Logistic regression analysis showed that the recurrence and metastasis of lung cancer after radical resection were related to smoking history,high tumor staging,medium and low differentiation,lymph node metastasis,MSI negative,and high TMB(P<0.05).The results of multivariate Logistic regression analysis showed that lymph node metastasis and high TMB were independent risk factors of postoperative recurrence and metastasis(P<0.05),while positive MSI was a protective factor(P<0.05).Both MSI and TMB were of evaluation value for postoperative recurrence and metastasis(P<0.05).There was no significant difference in AUC between MSI and TMB(P>0.05).There were significant differences in AUC between combined detection and MSI(P>0.05),but there was no significant difference between combined detection and TMB(P<0.05).Conclusion Both MSI and TMB have evaluation value for postoperative recurrence and metastasis.There are differences between combined detection and MSI,but there is no significant difference between combined detection and TMB,which indicates that single TMB has good detection value.

Key words: Microsatellite instability, Tumor mutation load, Non-small cell lung cancer, Postoperative recurrence and metastasis