Tubular damage marker as a predictive factor for pathologically upstaged renal cell carcinoma

To investigate if increased tubular damage biomarker can predict pathologically upstaged renal cell carcinoma (RCC), which may possess sub-radiologic invasive behavior, leading to surrounding tubular damage.

We examined 1563 patients with surgically resected RCC between March 2016 and June 2021 from the prospective database SUPER-RCC-Nx. Exclusion criteria were cancer not originating from the kidneys, benign renal tumor, and end-stage renal disease.

Of 1297 patients, 131 had a clinically high T stage (T3-4), whereas 1166 had a low one. Patients with a clinically low T stage were subgrouped into identical-stage (n = 1041) and upstaged (n = 125) groups, who were confirmed as a pathologically high T stage. The upstaged group had older age (p = 0.003), larger tumor size (5.72 ± 3.24 vs. 3.12 ± 2.08, p < 0.001), higher Fuhrman grade (grades 3-4) (57.3% vs. 47.1%, p = 0.032), and higher urine N-acetyl-beta-D-glucosaminidase/creatinine (NAG/Cr) (5.13 ± 4.78 vs. 4.05 ± 2.84, p = 0.026). Tumor size (> 4 cm; odds ratio = 10.2, p < 0.001) and urine NAG/Cr (odds ratio = 1.16, p = 0.003) were independently associated with pathological upstaging in patients with normal renal function, while age and tumor size were significant risk factors in those with decreased renal function. The receiver operating characteristic curve analysis showed that the model using tumor size and urine NAG/Cr strongly predicted pathological upstaging (area under the curve, 0.84).

Urine NAG/Cr may be a useful biomarker predicting pathologically upstaged RCC. Clinicians should be prudent in making management decisions when a large RCC is accompanied by an increased urine NAG/Cr.