The lymphatic system and its specific growth factor vascular endothelial growth factor C in kidney tissue and in renal cell carcinoma

OBJECTIVE To determine the role of vascular endothelial growth factor C (VEGF-C) and the quantitative extent of the lymphatic system in renal cell carcinoma (RCC) to analyse a possible correlation with the metastatic spread of cancer cells. PATIENTS AND METHODS In all, 44 patients with clear cell RCC and 12 with papillary or chromophobe RCC were included in an immunohistochemical study. The lymphatic vessel density (LVD) was assessed in the tumour body, the tumour capsule and the tumour-free adherent tissue. The expression of VEGF-C was semiquantitatively assessed by the percentage of positive epithelial and cancer cells. Data were analysed for any correlation with the clinicopathological variables. RESULTS The clear and papillary cell RCC contained no lymphatic vessels (0.2, SD 0.8). Chromophobe RCC specimens showed scattered obliterated vessels (0.0-7.7). Several lymphatic vessels were found in the normal renal tissue, mainly associated with blood vessels (2.9, SD 1.9). The highest mean (SD) LVD was in the tumour capsule, of 6.9 (3.4). There was no statistical correlation between the LVD and VEGF-C. In clear cell RCC the expression of VEGF-C was correlated with the size of the tumour (P = 0.042). CONCLUSIONS RCC does not promote the growth of its own lymphatic vessels. The role of a high LVD in the tumour capsule needs to be determined. The VEGF-C staining pattern in normal kidney tissue hints at functions other than lymphangiogenesis.