The biological significance of lymphangiogenesis in human tumours

Increasing evidence indicates that lymphangiogenesis in cancer is an important factor in promoting tumour progression and metastasis. The discovery of immunohistochemical markers for lymphatic vessels' identification as well as the characterization of lymphatic-specific growth factors and receptors afforded insight into the mechanisms involved in new lymphatic vessel formation and the process of lymphatic-borne metastasis. Quantitative assessment of lymphangiogenesis in malignant tumours has emerged as a promising prognostic indicator, although there are conflicting results on the impact of lymphatic vessel density to predict lymph nodal metastases and overall survival. Solid tumours were recently found to induce new lymphatic vessel growth in draining lymph nodes before the onset of metastasis and therefore lymphangiogenesis in the lymph nodes has gained great interest. This review highlights advances in our understanding of the mechanisms by which lymphangiogenesis in tumours and lymph nodes enhances metastases and reports the potential implications of these developments in cancer therapeutics.