 - Identify polymorphisms in metabolizing enzymes e.g., phase I or II metabolism GSTM1, GSTT1,CYP1A1, CYP3A5, mEH, NQO1, GSTP1, DNA repair XRCC1, ERCC2, free-radical formation MPO, MnSOD, inflammatory genes IL1-beta, metastatic potential MMP1, and cell cycle or tumor suppression p21, p53 and related path genes of susceptibility for esophageal cancer. 