OBJECTIVETo investigate the distribution patterns and proliferative activity of lymphatic vessels in colorectal carcinomas (CRC) and their relationship with tumor metastasis and disease prognosis.

METHODSThe microlymphatic density (MLD) and microvascular density in tumoral and non-tumoral areas of 96 cases of CRC were evaluated by immunohistochemistry, using monoclonal antibodies for podoplanin and CD34 respectively. The Ki-67 expression of the lymphatic and blood vessels was detected by double-labeling immunohistochemistry. The relationship between MLD and clinicopathologic features and prognosis was analyzed.

RESULTSThe lymph vessels at central and superficia1 portions of CRC often had a reticular architecture with numerous tiny and ill-defined lumina, while those at the tumor borders had large and open lumina. The MLD at tumor borders (51.2 +/- 25.5) was significantly higher than that in normal colorectal mucosa (29.4 +/- 9.0) and other portions of CRC (P < 0.01). The Ki-67 labeling index of the lymphatic lining cells at tumor borders (0.23 +/- 0.17) was significantly higher than that in other portions of CRC (P < 0.05). The MLD significantly correlated with lymphatic involvement by tumor cells, regional lymph node metastasis and distant metastasis (P < 0.01). The 5-year survival rate was also significantly lower in patients with high MLD (P < 0.05).

CONCLUSIONSNeolymphatic vessels are commonly seen in CRC, especially at tumor borders. High MLD at tumor borders is associated with metastasis. The detection of MLD at tumor borders may thus be useful in predicting lymph node metastasis and prognosis in patients with CPC.