Lymph belongs to the lymphatic system, which is the larger system of the body, like the blood system and the nervous system. The lymphatic system includes lymphatic vessels, lymph nodes, and lymphatic fluid inside the lymphatic vessels, which are collected into the thoracic duct and injected into the venous system. If inflammation of lymph nodes occurs, it can show painful swelling of lymph nodes with redness and swelling on the surface, which requires oral antibiotics for treatment. In case of painless lymph node enlargement, it is considered to be caused by tumor metastasis, because many tumors, such as stomach cancer and colon cancer, tend to metastasize in the direction of lymph nodes. If there is stomach cancer, or colon cancer, after the diagnosis is clear, it is recommended to perform radical tumor surgery.