Tumor angiogenesis and mode of metastasis in patients with colorectal cancer.

Neovascularization promotes tumor growth by facilitating nutrient exchange and by the paracrine effect. To investigate the relationship between tumor angiogenesis and patient outcome in colorectal cancer, 133 primary tumors were immunostained for CD34 antigen. Blood vessels within five microscopic fields at x200 were counted, and the mean was assigned. Mean patient age was 62.9 years, mean follow-up was 56.4 months, and mean vessel count was 112 (range, 23-298). Cox proportional hazards model and multivariate logistic regression analyses showed that the vessel count was the most important prognostic factor and correlated significantly with hematogenous, but not peritoneal or lymph node, metastasis.