MLH1 and esophageal cancer: In the initial results of the immunohistochemistry (IHC) tests for mismatch repair proteins (MMR) according to each type of solid tumor, it is noteworthy that in all cases (MSH2, MSH6, MLH1, PMS2), they remained intact in esophageal cancer, as well as in gastric cancer for MSH2 and MSH6.