Purpose: This study was designed to determine whether those rectal cancers that demonstrated increased vessel ingrowth or angiogenesis behave in a different fashion.
Methods: The paraffin blocks of 48 rectal cancers removed by low anterior or abdominoperineal resection were recalled and immunostained with a monoclonal antibody specific for endothelial cell Factor VIII. The intense reddish brown color imparted to blood vessels facilitated their quantification which was undertaken at x100 and x200 magnification. Vessel counts within three microscopic fields were averaged and the relationships between angiogenesis score and tumor size, depth of invasion, incidence of lymph node or distant metastases, and survival were assessed.
Results: Significantly higher angiogenesis scores were seen in tumors with transmural penetration (at x100, P = 0.002; at x200, P = 0.002) and in patients dying before five years (at x100, P = 0.013; at x200, P = 0.034). Although higher angiogenesis scores were seen in patients with larger tumors and metastases, these trends were not statistically significant.
Conclusions: Our results suggest that the growth of rectal cancer is dependent on the ingrowth of new blood vessels, and that increased vascularity promotes dissemination and adversely affects survival.