Objective: To describe the lymphatic vessel density and to determine the functional and prognostic significance of tumoral lymphatic vessels in upper tract urothelial carcinoma (UTUC).
Patients and methods: The study included 65 patients who had a radical nephroureterectomy (RNU) for UTUC between 1997 and 2004. All pathological slides were re-evaluated by one reference pathologist and clinical data were reviewed. Lymphatic endothelial cells (LECs) were stained immunohistochemically using D2-40. The lymphatic vessel density (LVD) was described in representative intratumoral (ITLVD), peritumoral (PTLVD) and non-tumoral (NTLVD) areas. Random samples were selected for double-immunostaining with D2-40 and CD-34 (to distinguish blood and lymphatic vessels) and the proliferation marker Ki-67 to detect lymphangiogenesis. The primary outcome measures were disease-specific survival (DSS) and disease recurrence (urothelial and/or distant).
Results: The median (interquartile range) PTLVD was 4.0 (3.0-6.3), and significantly higher than that for ITLVD, of 0.3 (0-1.7) (P < 0.001), and NTLVD, of 3 (2.0-3.7) (P < 0.001). Both a higher ITLVD and PTLVD, the presence of lymphovascular invasion (LVI) (each P < 0.001) and a high tumour grade (P = 0.004) were associated with reduced DSS on univariate analysis. A higher PTLVD (P = 0.028) and the presence of LVI (P = 0.020) independently predicted reduced DSS on multivariate analysis. IT and PT lymphatic vessels showed proliferating LECs in all analysed samples.
Conclusion: Lymphangiogenesis is present in UTUC, as shown by a significantly increased PTLVD and proliferating LECs. Our findings suggest functional relevance of PT lymphatic vessels during lymphatic tumour spread. PTLVD is a potential novel prognostic factor for DSS in UTUC, and further prospective studies will be needed to determine the effect of its routine evaluation on clinical outcomes of this malignancy.