Predictive Performance of Prospectively Applied ISUP and Fuhrman Grade in Nonmetastatic Renal Cell Carcinoma.

Background/aim: In 2012, the International Society of Urological Pathology (ISUP) recommended replacing Fuhrman with ISUP for grading renal cell carcinoma (RCC). Our aim was to report recurrence-free survival (RFS) and assess prognostic value of ISUP and Fuhrman for predicting recurrence using original pathology assessment and routine follow-up data.

Patients And Methods: In this single-institution retrospective cohort study, 686 patients underwent a single session total or partial nephrectomy due to nonmetastatic RCC (nmRCC). Of those, 564 had tumors prospectively graded according to either ISUP or Fuhrman, which defined the cohorts. RFS was defined as the interval from surgery to local recurrence and/or metastasis. Differences in RFS were calculated with log rank test. Cox models adjusted for risk factors were used for predicting recurrence.

Results: During a median follow-up of 36 months in the ISUP group (n=152), 11% developed recurrent disease. RFS was significantly lower for grade 4 compared to 1-3 (p<0.001), but non-significant between 1-3. Grade was the only significant predictor in multivariate analyses. During a median follow-up time of 50 months in the Fuhrman group (n=412), 16% developed recurrent disease. There was a significant difference in RFS between grades 2 and 3 (p=0.003) and between 3 and 4 (p<0.001), but non-significant between 1 and 2 (p=0.063). Grade, positive surgical margin, tumor size ≥4 cm, and pT were significant predictors of recurrence in multivariate analyses.

Conclusion: ISUP grading alone is an accurate tool for predicting recurrence in patients with nmRCC.