Prognostic significance of intratumoral microvessel density in canine soft-tissue sarcomas

The prognosis of canine soft-tissue sarcomas (STS) has traditionally been based on histologic grading. We have recently demonstrated the prognostic value of cellular proliferation markers in canine STS. Another method of predicting the behavior of neoplasms is intratumoral microvessel density (IMD), which is a measure of tumor angiogenesis. The prognostic significance of IMD has been documented in many human neoplasms and in a limited number of canine and feline neoplasms. To evaluate the prognostic value of IMD in canine STS, we studied 57 STS and compared IMD with histologic features, histologic grade, cellular proliferation, metastatic propensity, and survival. Using immunohistochemistry, the STS were labeled with anti-factor VIII-related antigen (FVIII-RA) and anti-CD31 antibodies to determine 3 IMD parameters: mean microvessel density, high microvessel density, and microvessel area. Using FVIII-RA and CD31, increasing IMD was statistically associated with increasing histologic grade, necrosis scores, and mitotic scores. Higher FVIII-RA IMD values were significantly associated with higher median argyrophilic nucleolar organizing region (AgNOR) values (as previously investigated) and increased metastatic propensity. Fibrosarcomas appear to be the least vascularized of STS. There is no correlation between IMD and survival. Our results indicate that IMD is of prognostic value for histologic grade, histologic features, cellular proliferation (based on AgNOR), and metastatic propensity of canine STS, specifically when using FVIII-RA as the endothelial marker. Assessing histologic grading, cellular proliferation, and IMD of canine STS at the time of diagnosis could therefore provide better prognostic information for the veterinary clinician.