To analyze the correlation of Microsatellite instability (MSI) status, clinicopathological features and prognosis of patients with II and IV stage colon cancer, therefore to predict pathological staging and prognosis of patients with colon cancers.

A total of 271 patients with colon cancer in our hospital from March 2010-May 2017 were enrolled into this prospective study. According to MSI status, patients were divided into high frequency MSI group, low frequency MSI group and the microsatellite stability (Microsatellite stability, MSS) group. Statistical analysis were performed by using SPSS18.0 software. Total survival time were expressed as mean±standard deviation, and were examined by t-test. The survival and clinicopathological characteristics of patients in each group were expressed as percentage (%), and was examined by chi-square test. The influencing factors were analyzed by multivariate Logistic regression model. A P value <0.05 was considered as significant difference.

Among 271 patients, 108 cases were high frequency MSI, 86 cases were low-frequency MSI, while 77 cases were MSS, with MSI of 71.6%(194/271). Total survival time of (26.2±3.8) months in high frequency MSI group were, higher than (18.2±2.7) months and (17.6±2.6) months in low frequency MSI group and in MSS group respectively, with significant difference (P<0.05). There were significant differences in terms of age, tumor location and pathological type, between high frequency MSI group, low-frequency MSI group and MSS group (P<0.05). Multiple factor Logistic regression analysis showed that the death was a dependent variable during the follow-up period, while the age < 65 years and high frequency MSI were protective factors, and lymph node metastasis was an independent risk factor affecting the prognosis of patients (P<0.05).

There were high incidence of MSI in patients with stage II and IV colon cancer.Patients with high frequency MSI exhibit clinicopathological features, including young age, tumor location in right hemicolon and mainly of adenocarcinoma, importantly with pretty good prognosis.