Introduction:
The prognosis of patients treated with surgery for localized renal cell carcinoma (RCC) is associated with multiple factors, which has led to the development of various prognostic models to predict progression-free survival (PFS) and cancer-specific survival (CSS). The ability to predict future oncologic events has broad implications for patient counseling, clinical trial design, and informing surveillance regimens. Surveillance regimens must balance factors including patient/disease characteristics, cost, and likelihood/timing of progression. The AUA guidelines recently introduced a new risk stratification system based on tumor stage and grade to guide surveillance after partial and radical nephrectomy. We sought to evaluate the new AUA risk stratification system with respect to PFS and CSS at the suggested follow-up intervals. Additionally, we compared the predictive performance of a published institutional (Mayo) risk model to the new AUA risk stratification system.
Methods:
We queried the Mayo Clinic Nephrectomy Registry to identify adults treated with radical or partial nephrectomy for unilateral, sporadic, M0, clear cell or papillary RCC between 1980 and 2012. Chromophobe RCC was unable to be risk stratified by the AUA schema because the WHO/ISUP does not grade this subtype of RCC. Progression was defined as local ipsilateral recurrence, regional lymph node involvement, distant metastases, or death from RCC. Clinical and pathologic features were used to calculate scores for patients with clear cell RCC and papillary RCC from an institutional model (outlined in European Urology 2018, PMID 29398265). PFS and CSS were estimated using the Kaplan-Meier method. Predictive abilities of the AUA risk groups and the Mayo models were evaluated using c-indexes from Cox proportional hazards regression models.
Results:
3,191 patients with clear cell RCC and 633 patients with papillary RCC were available for study with a median follow-up of 12 (IQR 8.8-16.5) and 9.8 (IQR 5-15.3) years, respectively. PFS rates by AUA risk group for patients with clear cell RCC and papillary RCC are summarized in Table 1 and (for clear cell RCC) Figure 1. For patients with clear cell RCC, c-indexes for the AUA risk groups and the Mayo model were 0.780 and 0.815, respectively (p<0.001), for progression and 0.811 and 0.857, respectively (p<0.001), for death from RCC. For patients with papillary RCC, c-indexes for the AUA risk groups and the Mayo model were 0.775 and 0.751, respectively (p=0.002), for progression and 0.830 and 0.803, respectively (p=0.2), for death from RCC.
Conclusion:
For the first time, we demonstrate that the new AUA risk stratification system has robust c-indexes for PFS and CSS in patients with clear cell RCC and papillary RCC after surgery for localized kidney cancer. The 2018 Mayo model performed better than the AUA risk stratification system for PFS and CSS in patients with clear cell RCC whereas the AUA risk group was better for papillary RCC. However, there was a significant difference in PFS rates between clear cell RCC and papillary RCC at the recommended follow-up intervals based off of AUA risk group. A major limitation of the AUA risk stratification scheme is that it does not apply to chromophobe RCC, as it relies on WHO/ISUP grading, which does not currently grade chromophobe RCC.
Funding: N/a
Image(s) (click to enlarge):
MAYO CLINIC VALIDATION OF AUA RISK GROUPS FOR LOCALIZED RENAL CANCER
Category
Kidney Cancer > Localized
Description
Poster #21
Wednesday, Dec 1
2:00 p.m. - 3:00 p.m.
Kidney 1
Presented By: Andrew Zganjar
Authors:
Andrew Zganjar
Paige Nichols
Christine Lohse
John Cheville
Sounak Gupta
Aaron Potretzke
R. Houston Thompson
Bradley C. Leibovich
Stephen A. Boorjian
Vidit Sharma