Therefore, we determined DNA damage in selenium compounds treated in three ESCC cell lines after 1 and 3 days of incubation by the presence of the phosphorylated histone variant H2AX (γ-H2AX) and 8-hydroxydeoxyguanosine (8-OHdG) in the nucleus. The gene discussed is H2AX; the disease is esophageal squamous cell carcinoma.