Circulating KIM-1 as a prognostic biomarker and predictor of systemic treatment response in renal cell carcinoma: a systematic review and meta-analysis.

BACKGROUND: Renal cell carcinoma (RCC) exhibits heterogeneity and variable responses to systemic therapy. Kidney injury molecule-1 (KIM-1) has emerged as a biomarker in RCC, but its prognostic and treatment-response value has not been quantified. This review and meta-analysis evaluated whether baseline KIM-1 predicts survival in RCC and whether post-treatment changes in KIM-1 reflect systemic therapy response. METHODS: A search of PubMed, Embase and the Cochrane Library was conducted through November 2025. Eligible studies measured serum or plasma KIM-1 in RCC and reported survival or treatment-response outcomes. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled. RESULTS: = 71.5%) and improved disease-free survival (HR 0.66, 95% CI 0.50-0.87). CONCLUSIONS: Elevated baseline circulating KIM-1 indicates higher RCC recurrence and mortality risk, while post-treatment declines may reflect therapeutic response. Preliminary evidence suggests KIM-1 prognostic and predictive value for RCC biomarker, though further validation is required due to lower certainty.