Organ-confined clear cell renal cell carcinoma: the prognostic impact of microvascular invasion, nuclear grade and tumour size.

The frequency of diagnosed and treated organ-confined renal cell carcinoma is increasing. The prognosis of this group of tumours is difficult to predict. The main purpose of this study was to examine the prognostic significance of microvascular invasion, tumour size and nuclear grade in a complete cohort of 76 consecutive patients with organ-confined clear cell renal cell carcinoma treated with radical nephrectomy. Patient ages ranged from 39 to 88 years (mean 66 years). Median follow-up was 10.2 years (range 0.1-19.4 years). The tumours were graded according to Fuhrman. Representative histological sections were stained for CD31, which decorates endothelial cells, in order to assess microvascular invasion (MVI). In univariate analysis, microvascular invasion (p<0.01), tumour size (TS) (p=0.01), TNM stage (p=0.01) and Fuhrman nuclear grade (p=0.02) were significant predictors of cancer-specific survival. Multivariate analysis, adjusted for age, revealed that microvascular invasion, tumour size and nuclear grade were independent covariates. According to our findings microvascular invasion is a strong independent prognostic predictor, and including this in the histopathology report should be considered together with nuclear grade and tumour size.