Oncology - Bladder, Renal, Test
Mid-Atlantic Section 76th Annual Meeting
Introduction & Objective : Clinical utility of renal mass biopsy (RMB) for differentiating benign from malignant tumors is well-established; however, its ability to accurately predict tumor grade remains controversial. Indeed, grade concordance reports in the literature vary. Here, we query four large institutional kidney cancer surgical cohorts to better understand how the prevalence of high-grade disease affects RMB tumor grade concordance rates.
The prospectively maintained kidney cancer databases of 3 large volume centers across the State of Pennsylvania and 1 from Michigan were queried for the histopathological characteristics (pathological size, histology, nuclear grade) of resected pT1a renal masses. Only masses with clear cell histology and those with a documented nuclear grade were included in the analysis. The prevalence of HG disease, defined as Fuhrman nuclear grade 3 or 4 was calculated for each center. Using the biopsy sensitivities from the largest RMB series to date (Richard et al Eur Urol, 2015), we then calculated the expected RMB grade concordance rate and negative predictive value for RMB at each participating site.
A total 1740 patients met criteria for analysis. The institutional prevalence of high-grade disease markedly varied from 13.6% to 37.9% (Table 1). Increased prevalence of HG disease was associated with a decrease in RMB overall grade concordance rates (94.1% to 83.7%) and reduced negative predictive value (93.6 to 79.2%) (Table 1).
Conclusions : The prevalence of high-grade disease in patients with a renal mass significantly varies even among institutions in the same state and across state lines. In turn, rates of high-grade disease have a significant impact on tumor grade concordance at RMB. As such, each institution must be cognizant of its case-mix and interpret RMB results accordingly.