Lymphangiogenesis And Its Role Of Lymphatic Metastasis In Rectal Cancer

BACKGROUND: The incidence rate of rectal cancer increases gradually in China, and its prognosis and survival rate is associated with multiple factors, including local infiltration, distant metastasis, and lymphatic node metastasis. Recently, the relevant studies indicate that newly bora lymphatic vessels, which exited in mostly solid tumors, and its relative vascular endothelial growth factors are associated with lymphatic metastasis and may play a significant role in revealing the mechanisms of lymphatic metastasis in solid tumors. In this study, utilizing single staining and double staining technique of immunohistochemistry, we labeled newly born lymphatic vessels in rectal carcinomas and mucosas of normal rectal tissues, found morphological features of lymphatic vessels in rectal cancer and analyzed the relationship between lymphangiogenesis and clinical pathological parameters.OBJECTIVE:. To investigate the characteristics of newly born lymphatic vessels and the proliferative activity of lymphatic endothelial cells in rectal cancer, as well as their relationship with lymphatic metastasis.MATERIALS AND METHODS: Utilizing antibody to Ki-67 antigen as a marker of cell proliferation, and antibody to podoplanin as a lymphatic vessel-specific marker, 52 sections taken from patients with rectal cancer were labeled proliferating lymphatic vessels using single immunostaining and double immunostaining methods. 10 normal rectal tissues taken from patients who under resection of procedure for prolapse and hemorrhoids(PPH) were randomly selected as controls. Then we calculated lymphatic microvessel density (MLVD) and Ki-67 labeling index, studied the features of newly bora lymphatic vessels and proliferative activity of lymphatic endothelial cells, and analyzed the relationship between lymphangiogenesis in rectal cancer and patients' clinicopathological variables.RESULT: The lymphatic vessels at intratumoral regions in rectal cancer often had reticular architecture with numerous tiny and ill-defined lminas, while those at peritumoral regions had large and open luminas. The MLVD of peritumoral areas(MLVDpt) (34.85±10.68) was significantly higher than that in normal rectal mucosa(l 1.80±3. 39) and intratumoral areas of rectal cancer(P <0.01). The Ki-67 labeling index of the lymphatic endothelial cells at peritumoral areas(0.26±0. 05) was significantly higher than that in intratumoral areas of rectal cancer(0.03±0. 02). The MLVD significantly correlated with lymphatic involvement by tumor cells, regional lymph node metastasis and distant metastasis(P <0.01 or P<0.05).CONCLUSION: 1. Newly born lymphatic vessels are commonly seen in rectal cancer, especially in peritumoral areas;2. Compared with the intratumoral areas in rectal cancer and normal rectal tissues, both the MLVD and the proliferative activity of lymphatic endothelial cells were increased more significantly in peritumoral areas of rectal cancer.3. The increased MLVDpt in rectal cancer may be associated with lymphovascular invasion, lymphatic node metastasis and distant metastasis, furthermore, the detection of LMVD in rectal cancer may be valuable in predicting lymphatic metastasis.