Background: It has been postulated that tumors beyond a certain size are dependent on angiogenesis, which might also be related to distant metastasis. We therefore assessed the prognostic significance of tumor microvasculature in renal cell carcinoma.
Methods: Tumor specimens from 84 patients with primary renal cell carcinoma were examined by immunohistochemical staining for factor VIII. Individual microvessels were counted in a 200 x field overlying the area of highest neovacularization.
Results: The mean number of microvessels in patients with metastases was significantly higher than that in patients who were disease-free for more than three years (P = 0.004). The survival of patients with less than 30 microvessels per 200 x field was significantly higher than that of patients with more than 30 microvessels per 200 x field (P = 0.007). Multivariate analyses revealed that these microvessel counts were the only significant predictor of prognosis in 45 patients with T1-2 and M0 tumors (P = 0.028).
Conclusions: Assessment of tumor microvasculature is therefore probably one of the most important prognostic predictors in renal cell carcinoma.