In this respect, it is interesting to note that a comparison of the prevalences of gene mutations obtained by multiregional sequencing provides figures quite different from those obtained by single-sample analysis (e.g., 8% SMAD4 mutations in the TCGA data set, 15% in a series of 551 esophageal adenocarcinomas, and 33% in our dataset; Additional file 2: Table S13) [3, 43]. This evidence concerns the gene SMAD4 and esophageal adenocarcinoma.