ABSTRACT
Lymph node metastasis of malignant tumor is a complex pathological process closely related to tumor lymphangiogenesis. With tumor growth, some growth factors of lymphatic vessels are secreted and new lymphatic vessels are formed around or inside the tumor. Then, the tumor cells invade the lymphatic vessels, follow the lymph flow into every lymph node station, and gradually form the lymph node metastasis. Normal cells are in a relatively stable internal environment. Cell proliferation, differentiation, and apoptosis, as well as secretion and expression of related factors, occur in accordance with the normal process. However, the balance is broken with tumor growth and progression. A gradual formation of a suitable external environment for the tumor growth, namely, the tumor microenvironment, occurs. And the pathological and physiological characteristics of tumor microenvironment, which contains numerous lymphangiogenic growth factors and inflammatory conditions, hypoxia, acidic microenvironment, and high interstitial fluid pressure, promote tumor lymphangiogenesis and formation of tumor lymph node metastasis.
