The origin of lymphatic vessels involved in metastasizing of neoplastic cells in squamous cell carcinoma of the uterine cervix

Abstract

In many human malignant tumors the lympho-vascular metastasizing represents the main way of tumor-modified cells spreading. Lymphatic vessels invasion by the neoplastic cells leads to the involvement of regional lymph nodes (RLN) in tumor process. It is well known that metastatic damage of RLN correlates with poor outcome. Tumor cells secrete biological active substances that lead to the appearance of newly formed blood network which keeps up the metabolic activity inside the tumor. Tumors also produce growth factors for lymphatic endothelial cells. Until now it is not clearly established, tumor cells invade the preexistent peripheral lymphatic vessels or invade the newformed vessels which are formed during tumoral lymphangiogenesis. To establish the origin of lymphatic vessels (LM) involved in metastatic spreading of neoplastic cells in squamous cell carcinoma (SCC) of the uterine cervix. There were investigated the postoperative material taken from patients with SCC of the uterine cervix (n=39). All material was stained with hematoxylim Harris and eosin. For immunohistochemical (IHC) procedure were selected only the cases with intravascular tumor emboli (n=30). Two monoclonal antibodies were used: anti D2-40 (RTU clone, DakoCytomation, Denmark) to highlight the LV and anti Ki-67 (DakoCytomation Carpinteria, CA, USA) for identification of proliferated endothelial cells. The IHC reaction was performed in accordance with Avidin-Biotin technique (LSAB+/Double Stain). Nuclei were stained with Lillie’s modified Hematoxylin. The entire IHC procedure was performed with DakoCytomation Autostainer. There were counted only the LV with the tumor emboli inside. The LV which were positive only for anti D2-40 were considered to be the preesisting vessels, and that LV which were positive for both of the antibodies were considered to be the newly-formed, tumor-derived vessels. LV were found in intratumoral and peritumoral areas. All intratumoral LV were small and flattened, without lumen. Lymphatics placed at the periphery of tumor nests were relatively large and perfusable (with well distinguished lumen). There were found 24 lymphatics with emboli inside. All of them were placed in the peritumoral area. Were detected 11 (45,83%)LV with proliferated endothelial cells. Size of proliferated LV were smaller than size of preexisting lymphatics. There were not found any correlation between the distance of proliferated and preexisting LV from the invasive front of the tumor. Relatively few studies addressed to lymphangiogenesis in neoplastic lesions of the uterine cervix. From them, some addressed to the prognostic value of the lymphovascular invasion in relation with lymph node status and systemic metastasis. It was found that metastases is significantly higher in patients with lymphovascular invasion than in cases without, as otherwise expected. D2-40 is a specific and the most sensible marker for lymphatic endothelial cells. Ki-67 is a nuclear marker which is positive in dividing cells. LV with metastatic emboli were found only at the periphery of the tumor mass. These data show that peritumoral LV are involved in metastatic spreading of tumor cells. Formation of new LV begins with proliferation of their endothelial cells. We use Anti Ki-67 to highlight these mitotically active cells. The size of LV with Ki-67 positive cells were smaller than the size of preexisting LV, which shows that these lymphatics are younger. The high amount of newlyformed LV with emboli inside proves that tumor derived lymphatics participate in metastatic dissemination. Conclusions. 1) Lymphovascular metastasizing in squamous cell carcinoma of the uterine cervix occurs through peritumoralLV 2) neoplastic cells disseminate either through preexisting LV and newly-formed.