Validation of urine p-cresol glucuronide as renal cell carcinoma non-invasive biomarker

Renal cell carcinoma (RCC) stands among the most lethal urological malignancies. Most RCCs are incidentally diagnosed as initial symptoms are unspecific. Novel, minimally-invasive diagnostic and prognostic methods for RCC are needed, ideally in urine. Using UPLC-Q-ToF MS untargeted metabolomic analysis in urine, we previously revealed p-cresol glucuronide as potential RCC diagnostic marker. Additionally, urine samples one-year post-nephrectomy revealed isobutyryl-l-carnitine and L-proline betaine as potential RCC prognostic markers. Our present aim was to validate these differences in an independent cohort of RCC patients and healthy controls to strengthen their value as non-invasive biomarkers. In an independent cohort of 69 RCC patients and 52 controls we validated an increase in p-cresol glucuronide in urine from patients at diagnosis compared to controls (P = 0.0043). It remained increased one-year post-nephrectomy (P = 0.0288). The value of p-cresol glucuronide for RCC diagnosis was assessed with ROC curves analysis (AUC = 0.66, 95 % Confidence Interval 0.56-0.76). The role of isobutyryl-l-carnitine and L-proline betaine as prognostic markers could not be validated and will require a larger cohort. Our findings confirm the value of p-cresol glucuronide in urine as diagnostic marker for RCC in an independent cohort. This non-invasive method holds promise for enhancing patient care by reducing the need for potentially risky diagnostic procedures. Further metaproteomics-oriented approaches towards the tyrosine oxidation pathway and microbiota metagenomics studies may promote a holistic management of RCC. SIGNIFICANCE: Current imaging techniques available to diagnose and monitor renal cell carcinoma (RCC) are harmful for the patient given the high-radiation dose, and unspecific in low-grade tumors. Thus, novel non-invasive biomarkers with diagnostic and prognostic capabilities are of utmost importance. Herein, we have validated urine p-cresol glucuronide as diagnostic marker for RCC. This novel non-invasive biomarker could improve accurate assessments of tumor behavior, while enhancing patient outcomes by reducing discomfort and detrimental side effects.