Comparison of microsatellite status detection methods in colorectal carcinoma

Mei-Li Chen; Jie-Yu Chen; Jing Hu; Qian Chen; Li-Xia Yu; Bao-Rui Liu; Xiao-Ping Qian; Mi Yang

Comparison of microsatellite status detection methods in colorectal carcinoma

Int J Clin Exp Pathol. 2018 Mar 1;11(3):1431-1438. eCollection 2018.

Authors

Mei-Li Chen^{1

2}, Jie-Yu Chen³, Jing Hu¹, Qian Chen⁴, Li-Xia Yu¹, Bao-Rui Liu¹, Xiao-Ping Qian¹, Mi Yang^{1

2}

Affiliations

¹ The Comprehensive Cancer Center of Drum Tower Hospital, Medical School of Nanjing University and Clinical Cancer Institute of Nanjing University Nanjing 210008, China.
² Medical School of Southeast University Nanjing, Jiangsu, China.
³ Department of Pathology, Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School Nanjing, China.
⁴ Nanjing Drum Tower Hospital Group Suqian People's Hospital Suqian, China.

PMID: 31938240
PMCID: PMC6958115

Abstract

There are two commonly accepted methods for detecting microsatellite status. One is to detect amplified microsatellite loci by polymerase chain reaction (PCR) and the other is to detect mismatch repair gene (MMR) protein expression by immunohistochemistry (IHC). PCR detection is considered to be accurate in clinical operations while IHC is widely used due to ease of operation and lesser expense. In order to compare IHC with PCR in detecting microsatellite status in colorectal carcinoma, a total of 569 samples of colorectal carcinoma resection were collected in the Department of Pathology, Nanjing Drum Tower Hospital, between June 2014 and June 2017. In all samples, IHC and PCR was used to detect microsatellite status and the consistency of results between the two methods was compared. We found that 48 cases of microsatellite instability (MSI) were detected by PCR including 37 cases of microsatellite instability high (MSI-H), 11 cases of microsatellite instability low (MSI-L), and 521 cases of MSS. MSI accounted for 8.44% of all cases and MSI-H accounted for 6.50%. IHC results of the 569 patients showed that 69 cases were deficient mismatch repair (dMMR) and 500 cases were proficient mismatch repair (pMMR). dMMR accounted for 12.13% of all cases. Loss expression of PMS2 protein was the most common while MSH6 was rare. The coincidence rate of the two methods for detecting microsatellite states was 91.92%. IHC and the PCR method had high consistency in microsatellite status. Compared with PCR, the IHC method is more economical and more convenient for clinical operations. When the 4 repair proteins were without deficiency detected by IHC, it could be diagnosed as MSS/MSI-L and further PCR was not necessary. When any repair protein was found to be deficient, PCR detection was needed to determine whether MSI existed. Our conclusion will save a lot of time and costs in clinical work.

Keywords: Immunohistochemistry (IHC); colorectal carcinoma; microsatellite instability (MSI); mismatch repair gene (MMR); polymerase chain reaction (PCR).