Transcription factors Slug and Snail were strongly expressed in Kazakh ESCC specimens, and their expression was significantly correlated with reduced E-cadherin expression (r = −0.648, P < 0.001 and r = −0.594, P < 0.001, respectively; Additional file 3: Table S3). This evidence concerns the gene SNAI1 and esophageal squamous cell carcinoma.