Early detection of kidney cancer using urinary proteins: a truly non‐invasive strategy

Objectives To review urinary protein biomarkers as potential non‐invasive, easily obtainable, early diagnostic tools in renal cell carcinoma (RCC). Methods A PubMed database search was performed up to the year 2020 to identify primary studies reporting potential urinary protein biomarkers for RCC. Separate searches were conducted to identify studies describing appropriate methods of developing cancer screening programmes and detection of cancer biomarkers. Results Several urinary protein biomarkers are under validation for RCC diagnostics, e.g. aquaporin‐1, perilipin‐2, carbonic anhydrase‐9, Raf‐kinase inhibitory protein, nuclear matrix protein‐22, 14‐3‐3 Protein β/α and neutrophil gelatinase‐associated lipocalin. However, none has yet been validated or approved for clinical use due to low sensitivity or specificity, inconsistencies in appropriate study design, or lack of external validation. Conclusions Evaluation of biomarkers’ feasibility, sample preparation and storage, biomarker validation, and the application of novel technologies may provide a solution that maximises the potential for a truly non‐invasive biomarker in early RCC diagnostics.