Before PSM, there were no differences in age, sex, BMI, smoking and alcoholism, adjuvant therapy, pTNM stage, pathology type, tumor location, surgical resection range, tumor diameter, distant metastasis, regional lymph node metastasis, lymph node metastasis rate, vascular infiltration, nerve infiltration, CEA, CA199 between the two groups, but there was significant difference in borrmann type (P < 0.001, Table 1). This evidence concerns the gene CEACAM5 and alcohol dependence.