Prognostic value of plasma vascular endothelial growth factor in patients with colorectal cancer

Background: Vascular endothelial growth factor (VEGF) is thought to be the most powerful angiogenic factor in many malignancies while and several reports have determined serum VEGF to be a prognostic indicator for various malignancies. However, serum VEGF may not be suitable for the measurement of circulating VEGF levels, given that clot formation during the process of collecting sample induces platelet activation and the subsequent release of many cytokines. Materials and Methods: Blood samples were obtained prior to surgery from 33 patients with colorectal cancer, and additional samples were obtained 6 months post-operatively from 15 of the 33 patients. Plasma levels of VEGF were assessed using the quantitative sandwich-enzyme immunoassay technique. We investigated the relationships between plasma levels of preoperative VEGF, prognosis and clinicopathological factors in patients with colorectal cancer. In addition, the relationship between pre-operative and post-operative plasma levels of VEGF obtained at 6 months was assessed. Results: Although not significant, a trend was observed for high plasma levels of VEGF to occur with more advanced colorectal cancer. Plasma levels of VEGF were only significantly increased in patients who had recurrence and a worsening of colorectal cancer. In blood samples obtained from 15 patients both prior to surgery and 6 months post-operatively, post-operative mean plasma VEGF tended to decrease relative to the pre-operative level. Conclusion: These results suggest that high plasma levels of VEGF may be observed in more advanced colorectal cancer patients, especially in patients who develop recurrence or a worsening of their condition. Thus, such patients may require additional immunochemotherapy after surgery.