[The role of immune system in colon metastasis. Lymphangiogenesis or lymphedema in cancer tissue].

The extent of lymph node metastasis is a major determinant for the staging and the prognosis of most human malignancies. Although the clinical significance of lymph node involvement is well documented, molecular mechanisms that promote tumor spread into the lymphatic or blood vascular systems and widespread dissemination are not well understood. Although there is a large body of evidence that newly visualized lymphatics facilitate formation of metastases, it remains unclear whether these are "new" or simply pre-existing dilated vessels. High level of permeability of tumor blood capillaries brings about high tissue fluid and lymph formation. The physical forces but not the putative cancer-produced VEGF C may be responsible for more lymphatics seen around cancer than in normal tissue. The main question to be answered is: are there morphologic and functional differences between newly formed and pre-existing intra- or peri-tumoral lymphatics? In our experience specimens of gastric and colon cancer revealed presence of peri-tumoral but not intra-tumoral lymphatics. Tumor tissue contained numerous tissue fluid "lakes" communicating with lymphatics. We speculate that increased production of lymph in the tumor tissue caused by high blood capillary permeability brings about dilatation of the interstitial space and peri-tumoral lymphatics. Excessive lymph flow may drag tumor cells. This article is reviews current literature on the role of angiogenesis and lymphangiogenesis in cancer metastasis with respect to own research.