Validation of a postoperative prognostic model consisting of tumor microvascular invasion, size, and grade to predict disease-free and cancer-specific survival of patients with surgically resected renal cell carcinoma

Objectives:   To determine the value of microvascular invasion, tumor size, and Fuhrman grade to predict the survival of patients with surgically resected renal cell carcinoma (RCC).
Methods:   A total of 771 consecutive patients (T1–4, Nx, M0) were retrospectively reviewed. For each patient with RCC, the prognostic Sao Paulo score (SPS) was calculated using the following variables: tumor size (>7 cm vs ≤7 cm), nuclear grading, and microvascular invasion. On the basis of SPS, patients were subdivided into low-risk (LR), intermediate-risk (IR), and high-risk (HR) groups. Disease-free survival (DFS) and cancer-specific survival (CSS) were estimated using the Kaplan–Meier method. Median follow-up was 80 months.
Results:   Median follow-up was 80 months. DFS rates after 5 years were 91.2%, 61.3%, and 51.9% in the original SPS LR, IR, and HR groups, respectively. CSS rates after 5 years were 94.3%, 79.8%, and 58.7%, respectively ( P  < 0.001). Each original SPS constituent revealed a significant influence on DFS and CSS in the multivariate analysis. By modification of the cut-off value of the maximum tumor size from 7 to 5 cm the predictive value of the SPS sum score was marginally enhanced. Using a cut-off value of 5 cm also resulted in a relatively better discrimination between the IR and the HR group regarding DFS and CSS.
Conclusions:   Stratifying RCC patients by SPS into LR, IR, and HR groups provides a clinically useful tool for outcome analysis and risk assessment. However, the prognostic value of the SPS could be enhanced by including a maximum tumor size with a cut-off at 5 cm into the sum score.