Lymphatic function, lymphangiogenesis, and cancer metastasis

The lymphatic system serves as the primary route for the metastasis of many cancers and the extent of lymph node involvement is the most important ind icator of tumor aggressiveness. Despite the apparent importance of the lymp hatic vessels for tumor dissemination, it has remained unclear whether acti vation of lymphatic endothelial cells may affect tumor progression and meta stasis and the molecular mechanisms of lymphangiogenesis are just beginning to be elucidated. This overview describes the unique structural and functi onal characteristics of the lymphatic vessels that render them particularly suitable for invasion by tumor cells and for their efficient transport to lymph nodes. Recent evidence indicates occurrence of tumor lymphangiogenesi s and its correlation with metastasis. Molecular regulation of tumor lympha ngiogenesis, its significance for tumor metastasis, and implications for ca ncer therapy are discussed. (C) 2001 Wiley-Liss, Inc.