We identified 96 articles (published between 2008 and 2021) using IHC expression of four proteins of the MMR system (MLH1, MSH2, MSH6, and PMS2) in EC, of which 73 used FFPE tissues, three used frozen tissue, and one used tumor cells [40,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142]. Here, MLH1 is linked to neoplasm.