PROGNOSTIC-SIGNIFICANCE OF MICROSCOPIC VASCULARITY FOR CLEAR-CELL RENAL-CELL CARCINOMA

Objective To investigate the association between tumour vascularity an d patient survival in a series of clear-cell renal cell carcinoma (RCC ), which often metastasizes via the vascular route and frequently has a prominent vascular network. Materials and methods Vessels were label led in sections from 150 cases of clear cell RCC by factor VIII immuno histochemistry. The mean microvessel density (MMD), expressed as the n umber of vessels per 10 high-power fields (HPFs, x 400, aggregate fiel d area 1.452 mm(2)) and tumour microvessel area (TMA), expressed as th e percentage of the total tumour area within 10 HPFs, were measured fo r each case, The relationship between MMD and TMA, tumour stage and gr ade, and patient survival over a 5-year followup was determined. Resul ts Tumour MMD ranged from 1 to 238 vessels per HPF, while the TMA was 1.2-60.8%. There was a weak but significant difference for MMD between tumour grades (P<0.01) and stages (P<0.05). There was no significant association between TMA and either tumour stage or grade. Division of cases according to MMD less than or equal to 40 and >40 per HPF showed a significant difference in survival curves between both groups, with a higher MMD being associated with longer patient survival, The signi ficant association between MMD and survival was retained for stage 3 t umours only when cases were stratified according to Robson's stage at presentation. TMA did not correlate with survival. Conclusions The ass essment of tumour vascularity is of prognostic significance for clear cell RCC. The significant inverse relationship between MMD and patient survival suggests that for tumours with a poor prognosis, decreased M MD is associated with tumour fibrosis and the development of large dia meter vascular channels.