A lumbar puncture was performed, and analysis of the cerebrospinal fluid (CSF) showed malignant cells (Figure 2), elevated protein, normal glucose, and the presence of tumor markers carcinoembryonic antigen and carbohydrate antigen19-9 She was diagnosed with metastatic leptomeningeal carcinomatosis of early gastric cancer and admitted to the hospital. This evidence concerns the gene CEACAM5 and gastric cancer.