ABSTRACT
The growth and maintenance of solid tumors are dependent on new capillary ingrowth:a process called "angiogenesis." Thus, after a new tumor has attained a smallsize of a few millimeters in diameter(about 106 cells), further expansion of the tumor-cell population requires the induction of new capillary blood vessels. These new vessels also increase the opportunity for hematogenous or lymph node metastasis. Thus this study was designed to examine the microvessel count at the invasive margin in colorectal carcinoma to determine how angiogenesis correlates with clinicopathologic factors and prognosis. Paraffinembedded tissues from 127 patients with primary colorectal carcinomas that had been completely removed were retrieved and analyzed for angiogenesis. Vessels were immunostained with anti-factor VIII polyclonal antibody, and areas with the most discrete microvessels were counted in a 200 x field, which were defined as angiogenesis score(AS). The mean AS for anti-factor VIII antibody in this study was 55+/-08; therefore, cases were classified into two subgroups : AS high group(n=67), for which AS was greater than 55 and AS low group(n=60), for which AS was equal to 55 or less. There were no significant intergroup difference regarding sex ratio, histologic grade, depth of invasion, or lymphatic invasion. AS was, however, significantly related to tumor size, venous invasion, lymph node metastasis, and liver metastasis(P=0.000, P=0.001, P=0.021, and P=0.004, respectively). The incidence of high AS group in Antler-Coller D was significantly greater than that in Antler-Coller A and B, and Antler-Coller C(P<0.05, respectively). The recurrence rate in high AS group was 32.0%, which was, though statistically insignificant, higher than that in low AS group(17.2%). The 3 year survival rates of high AS group were significantly (P=0.004 both for overall cases and curatively-resected ones) worse than those of low AS group. This study suggests that the growth of colorectal carcinoma is dependent on ingrowth of new blood vessels, and that angiogenesis assessed by the microvessel count using immunohistochemical stains is an important predictor of tumor behavior and may identify patients at higher risk for recurrence and early death.