The positivity rates for Cyclin D1 expression in the normal esophageal mucosa, esophageal squamous epithelial dysplasia or SCC in situ, and ESCC samples were 25.0% (15/60), 50.0% (30/60), and 67.6% (68/210), respectively, and the difference was statistically significant (P < 0.05). Here, CCND1 is linked to esophageal squamous cell carcinoma.