Study of monoclonal antibody Ki67 immunolabelling of renal cell carcinomaswith and without renal vein thrombosis.

Objectives : The objective of this study was to compare the proliferation i ndex (immunolabelling by monoclonal antibody Ki67 - MIB-1) of renal cell ca rcinomas as a function of the presence or absence of renal vein thrombus. A nalysis of the numbers of Ki67-positive nuclei can be used to assess the de gree of aggressiveness of the cell populations of these various cat-cinemas (tumour without thrombus, tumour with thrombus and neoplastic thrombus). Methods : Twenty three renal cell carcinomas with renal vein thrombus were matched for Furhman grade (Ist degree), tumour volume (2nd degree) and the patient's age (3rd degree) with 23 renal cell carcinomas not presenting any vascular embolus an histology. Monoclonal antibody MIB-1 immunolabelling w as performed on 69 paraffin-embedded specimens: 23 tumours with thrombosis, the 23 corresponding neoplastic thrombi and 23 tumours without vascular em bolus. Results : A correlation between Furhman grade and the percentage of immunol abelled nuclei was observed (mean: 2.67% for low-grade tumours and 14.34% f ar high-grade tumours). No labelling difference was observed between the tw o populations of primary rumours (with thrombus/without embolus). Primary t umours presented significantly weaker Ki67 labelling than their correspondi ng neoplastic thrombus (mean of 2.47% versus 10.3% p<0.01). Conclusion : This study shows that there is Ilo difference of the prolifera tion index between tumours with neoplastic venous thrombus and those with n o histological vascular embolus. However a difference of proliferation inde x was observed between the primary tumour and its corresponding thrombus, w hich presented a statistically higher immunolabelling. This finding suggest s that the thrombus possesses more dividing cells than the primary tumour i .e. has a shorter doubling time.