Koike sought to identify the population at high risk of lymph node metastasis among patients with clinical stage IA [54] and defined predictor factors such as age ≤ 67, preoperative serum carcinoembryonic antigen level ≥ 3.5 ng/mL, tumor size on preoperative radiologic findings ≥ 2 cm, and consolidation/tumor ratio on high-resolution computed tomography ≥ 89. Here, CEACAM5 is linked to metastatic malignant neoplasm in the lymph nodes.