摘要Objective: Angiogenesis is a crucial step for tumor growth and progression. Changes of liver angiogenesis (with-out metastatic invasion) in response to primary tumors are not known. The aim of the study was to investigate the liver angiogenesis in non-metastatic colorectal cancer (CRC). Methods: Human colorectal adenocarcinoma tumors were grown subcutaneously in nude mice. All animals showed tumor growth locally without macroscopic or microscopic evidence of liver metastases. Livers were investigated for their microvessel density (MVD) at different stages of tumor growth (as small, medium, and large-sized tumors). Normal non-tumor-bearing mice served as controls. To assess MVD, two endothelial cell markers (anti-CD34 and -CD31 antibodies), image analysis, and immunofluorescent technique were utilized. Enumeration of positive stained endothelial cells revealed the MVD. Results: Non-metastatic livers showed increased levels of MVD vs. control. Moreover, levels of MVD were higher in small and medium-sized tumor groups versus large sized tumor groups. Conclusion: The present data indicate that angiogenesis in the liver is induced in early-stages of CRC. However, this effect is suppressed with advanced tumor growth. These results provide an additional rationale for including antiangiogenic therapy in the treatment of early stages of CRC.