Lowenthal BM, Nason KS, Pennathur A, et al. - Whether ARID1A loss is related to prognosis and DNA mismatch repair (MMR) protein deficiency in esophageal adenocarcinoma, was determined in this study. Researchers performed immunohistochemistry to assess tissue microarrays signifying 316 surgically resected esophageal adenocarcinomas without neoadjuvant treatment, to determine ARID1A and MMR proteins. Morphologically, peritumoral lymphoid aggregates (90%) and tumor infiltrating lymphocytes (51%) were often displayed by ARID1A-loss adenocarcinomas. Longer overall survival was experienced by patients with ARID1A-loss adenocarcinomas (N = 22) vs those with ARID1A-retained adenocarcinomas, among patients having a locally advanced or metastatic disease (stages III or IV, N = 169). Overall, in esophageal adenocarcinoma, a link was identified between loss of ARID1A expression and DNA MMR protein deficiency. Findings also revealed an independent association of ARID1A loss with a more favorable prognosis for patients suffering from locally advanced or metastatic esophageal adenocarcinomas.