A multi-center retrospective study of MLH1 and PMS2 gene expression and clinicopathological features in 26 280 patients with colorectal cancer

Abstract

Objective To study the expression of MLH1 and PMS2 proteins and the characteristics of clinicopathological features. Methods A total of 205 071 patients with colorectal cancer data from 7 hospitals including the Chinese Academy of Medical Sciences Cancer Hospital from January 2010 to December 2018 were included in the study. 26 280 immunohistochemical information and case information met the research criteria. The relationship between MLH1 and PMS2 gene protein expression and age, sex, tumor size, pathological stage and other factors were analyzed. Results The MLH1 deletion rate was 4%, and the PMS2 deletion rate was 3.25%. There was a statistically significant difference in the ratio of male to female in the two patients with loss of protein expression (both P<0.001), and the age of onset was smaller than that in the normal expression group (both P<0.001). The incidence of the second primary cancer was also higher than that of the normal expression group (both P<0.001). The maximal tumor diameter of patients with MLH1 and PMS2 protein expression was greater than that of the normal expression group (all P<0.001), and the total number of lymph nodes cleared was also higher than the normal expression group (both P<0.001). In addition, the MLH1 expression-deficient group showed a clear tendency to familial aggregation compared to the normal group (P=0.001). At the site, the incidence of MLH1 and PMS2 protein deletions in the right colon was higher than in the normal expression group. In terms of tumor stage, the T stage of MLH1 and PMS2 protein was significantly different between the expression loss group and the normal group (P<0.001). In the M stage, the distant metastasis rate of patients with PMS2 protein deletion was lower than that of the normal group (P<0.001). Conclusion Patients with loss of MLH1 and PMS2 expression have earlier onset age, larger tumor volume, higher proportion of right colon, higher incidence of second primary cancer, higher number of lymph node dissection, and pathological staging. There is a close correlation. Key words: Colorectal neoplasms; Mismatch repair gene; MLH1; PMS2; Multicenter study; Big data platform