VEGF concentrations in tumour arteries and veins from patients with rectal cancer.

This pilot study investigated the hypothesis that the tumour itself is the source of the elevated vascular endothelial growth factor (VEGF) concentrations which are often observed in peripheral blood from patients with rectal cancer. Twenty-four consecutive patients with primary rectal cancer were included. Blood samples were drawn preoperatively from peripheral veins (I) and intraoperatively from peripheral veins (II), tumour arteries (III), and tumour veins (IV). In the four compartments, VEGF concentrations were measured in serum, EDTA plasma, and supernatants from lysed whole blood. Additionally, automated complete white cell and platelet counts were performed. In serum and EDTA plasma, no significant differences in VEGF concentrations were observed (p = 0.1 and p = 0.5), respectively) between tumour arteries and tumour veins. However, in supernatants from lysed blood, VEGF concentrations were significantly (p = 0.03) lower in venous blood than in arterial blood. Unexpectedly, a 16% reduction (p < 0.0001) in the number of neutrophils was observed during transit of the arterial blood through the rectal tumours, while none of the other types of leukocytes or platelets was significantly reduced in numbers during the same passage. These findings indicate that the tumour itself is not the only source of elevated VEGF concentrations in peripheral blood from patients with rectal cancer. A consistent finding was that a large number of neutrophils disappeared from the blood during passage through the rectal tumour. However, the significance and fate of the migrating neutrophils cells are unknown and should be investigated further.