[Prognostic significance of the microscopic invasion of the renal vein wall in renal cell cancer].

OBJECTIVES

International TNM Staging System for renal cell carcinoma (RCC) classifies as T3b when "tumor grossly extends into the renal vein or its segmental branches, or vena cava below the diaphragm". The finding of microscopic invasion of the vein wall is not taken into account for TNM staging. We analyse its prognostic significance in localized and locally advanced RCC.

METHODS

From January 1989 to July 2002, 257 RCC were surgically excised. Excluding Von Hippel-Lindau patients and stage IV (TNM 2002), 241 cases were studied in retrospect, with a median follow up of 50.96 months. Histopathological data from the renal vein were available in 216 specimens. There was renal vein wall invasion in 22. We compare the outcomes in this group vs. the group without microscopic involvement of the renal vein wall (n: 194).

RESULTS

Mean age for the group with renal vein invasion (RVI) was 65.02 years. Mean tumour size in the same group was 9 cm, larger than in control group (p<0,001). Thrombus was found in 72.7% vs. 6.2% in the control group. Clear cell carcinoma (77.3%) was the predominant histological subtype. Nuclear grade 2 according to Fuhrman's Classification System accounts for 42.9% of the cases. Metastatic progression risk (HR: 4,86) and death risk (HR: 6,49) are significantly higher in RVI group. When renal vein thrombosis is found, progression and death risks are still higher (HR: 7.22 and 8.38, respectively).

CONCLUSIONS

Microscopic invasion of the renal vein wall is a dependent prognostic factor for disease progression and death for RCC. Macroscopic renal vein involvement is an independent prognostic factor. When both factors are found together, disease outcome is worse.