Univariate analysis of the training set showed that there were significant differences in tumor size, lymph node metastasis, preoperative serum CEA level, Bacteroides abundance and Enterococcus abundance between patients with poor prognosis and patients with good prognosis (p < 0.05), as shown in Table 2. The gene discussed is CEACAM5; the disease is metastatic malignant neoplasm in the lymph nodes.