Does tumor size or microvascular invasion affect prognosis in patients with renal cell carcinoma?

Background: We retrospectively evaluated the effects of tumor size and microvascular tumor invasion on the clinical outcomes of patients who had undergone radical nephrectomy for renal cell carcinoma (RCC). Methods: One-hundred and sixty-two patients who received radical nephrectomy for localized or locally invasive RCC from1989 to 2002 were included. We evaluated a new cut-off value for tumor size by dividing patients into groups by tumor diameter from 3.0 to 7.0 cm in 1.0 cm increments and compared the prognosis with that predicted by the 2002 TNM classification. We also re-classified localized microvascular tumor invasion as invasive disease. Results: Univariate analyses showed a 5.0cm cut-off provided the greatest difference in recurrence (p = 0.004) and survival (p = 0.001). Microvascular invasion made no significant difference in tumor recurrence and tumor-specific survival. However, in the new categories used in this study, survival in the locally invasive group was poor compared with the localized group. Conclusion: Our study showed that a tumor diameter of 5.0 cm might be the critical size to determine the prognosis of patients with localized RCC. Microvascular invasion seemed to have the necessity of re-evaluation in the TNM classification for patients with RCC.