To evaluate which molecular biological factors are related to patients' prognosis and recurrence, we checked p53, p16, p21/Waf1, cyclin D1, Ki-67, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), Mdm2, Bcl2, E-cadherin and MRP1/CD9 by means of immunohistochemical analysis in 116 cases of oesophageal cancer (R0). This evidence concerns the gene CD9 and carcinoma of esophagus.