Narittee Sukswai M.D., Anapat Sanpavat M.D.
Faculty of Medicine, Chulalongkorn University
Introduction: Microsatellite instability(MSI) is one of the genetic abnormalities that leads to colon cancer. The defect, known as mismatch repair genes(MMR) can be either sporadic or a germ line mutation. A immunohistochemical study is one of the methods to detect MMR defects. Lots of different treatment modalities and prognosis are needed to distinguish cancer in this group from the APC pathway. Objective: To identify MMR defect in Thai patients.
Methods: Forty patients from King Chulalongkorn Memorial Hospital between year 2015-2016 were enrolled regarding modiﬁ ed Bethesda criteria then they received IHC screening, including MSH6 and PMS2. Cases with absolute loss of nuclear staining in either stains would be further stained by MLH1 and MSH2 to deﬁ ne a full proﬁ le for MMR defect.
Result: Four cases showed MMR defect; 2 of them had MLH1 loss, one of them had MSH2 loss and the last one had a loss of MSH6.
Conclusion: Ten percent of patients with colorectal cancer in our study had MMR defect which was in keeping with world prevalence of colon cancer. Further study or investigation to determine patients with MMR defect is needed to give proper treatment to patients and for planning genetic counselling.