| Objective: To analyze the differences in the expression of mismatch repair(MMR)proteins MLH1,MSH2,MSH6 and PMS2 in patients with colorectal cancer(CRC)and their relationship with the pathological features of CRC patients.Methods: The clinicopathological datas of 450 patients with colorectal cancer from January 2017 to September 2019 in the department of colorectal and anal surgery were collected from the first affiliated hospital of Guangxi Medical University.All cases by immunohistochemistry method to detect the expression of mismatch repair protein MLH1、MSH2、MSH6 and PMS2.One or more of the all MMR proteins were negative expression identified as the mismatch repair deficient(d MMR),and all positive expression was identified as the mismatch repair proficient(p MMR).All the cases were divided into d MMR and p MMR groups for comparative analysis of clinicopathological parameters to explore the relationship between mismatch repair protein expression and pathological factors such as sex,age,tumor location,tumor maximum diameter,pathological type,etc.Results :(1)Confirmed by immunohistochemistry method,among the 450 CRC patients,there were 370 cases in p MMR group,with a positive expression rate of MMR protein of 82.2%.There were 80 patients in d MMR group,and the MMR protein expression loss rate was 17.8%.The expression loss rates of MHL1,MSH2,MSH6 and PMS2 were 7.5%,7.1%,8.4% and 9.1%,respectively.The loss rate of MLH1/PMS2 co-expression was 6.2%,and that of MSH2/MSH6 co-expression was 5.8%.Through statistical analysis,the loss rate of both showed a significant positive correlation(γs =0.738,P < 0.001;γs =0.724,P < 0.001).In addition,the loss rate of MLH1/MSH2 co-expression was 0.2%(1/450).A total of 6 patients were deficient in 3 or more MMR proteins,and the loss rate was 1.3%.In addition,there were 2(0.4%)and 8(1.8%)cases of MLH1 and PMS2 expression deficient respectively.The expression deficiency of MSH2 and MSH6 alone was 5(1.1%)and 9(2.0%),respectively.(2)Compared with p MMR group,d MMR group had a younger onset age,and the difference was statistically significant(P=0.005).At the tumor location,d MMR group was more likely to occur in the right semicolon,while p MMR group was more likely to occur in the rectum and left semicolon(P < 0.001).In terms of tumor size,the d MMR group had a greater tumor load at the time of diagnosis(P < 0.001),and the tumor differentiation degree was more and tended to be low differentiation,with a statistically significant difference(P < 0.001).In terms of whether lymph node metastasis occurred or not,lymph node metastasis was less in the d MMR group(P < 0.05),and more in the TNM stage in the d MMR group in the early stage of tumor,that is,stage I ～II proportion was more(P < 0.05).The ratio of serum CEA value in the normal range before surgery in d MMR group was higher than that in p MMR group,and the difference was statistically significant(P=0.006).There were no statistically significant differences between d MMR group and p MMR group in gender,pathological type,histological type,depth of infiltration(T),distant metastasis(M),vascular infiltration,neurologic invasion,preoperative serum CA199,family history of tumor,second primary cancer,and the presence or absence of diabetes/hypertension(P >0.05).In terms of immunohistochemistry,the differences in CD34,D2-40 and ki67% were not statistically significant(P >0.05).Conclusion :(1)The expression loss rate of MMR protein in CRC patients is low,and the proportion of d MMR in colorectal cancer is small.In addition,the expression defective of MMR protein is mainly caused by the co-expression defective of MLH1/PMS2 and MSH2/MSH6,respectively,while the simultaneous defective of 3 or 4 MMR proteins is rare.(2)In the d MMR group,the pathological characteristics of colorectal cancer patients were that the age of onset was small,they were more likely to occur in early tumors of the right colon with a large tumor load,and they tended to have low-differentiated carcinoma and less lymph node metastasis.In addition,serum CEA values of colorectal cancer patients in d MMR group before surgery were mostly in the normal range.(3)In clinical practice,the expression of MMR protein in colorectal cancer can be detected by IHC method to further understand the types and proportions of MMR protein deficiency,so as to better distinguish between d MMR and p MMR colorectal cancer with two different pathological characteristics,and to recognize the important role of MMR protein in colorectal cancer... |
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