Circulating Tumor DNA in Patients with Renal Cell Carcinoma. A Systematic Review of the Literature

CONTEXT: Over the past decade there has been increasing interest in the potential of liquid biopsies and systematic biomarkers in the diagnosis and management of kidney cancer, as they may provide a tool for early detection of disease and monitoring of treatment response. OBJECTIVE: To identify and summarize relevant published data on circulating tumor DNA (ctDNA) in patients with renal cell carcinoma (RCC). EVIDENCE ACQUISITION: We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement of studies identified in PubMed, MEDLINE, EMBASE, and Cochrane Library up to January 15, 2021. Two reviewers independently screened all articles and performed the data extraction. EVIDENCE SYNTHESIS: Nineteen studies investigating ctDNA in RCC (1237 patients) were included and analyzed in the final review. The study size and design varied widely, and the studies were divided into five groups according to the method used for ctDNA detection. The outcome data included (1) the sensitivity/specificity if available; (2) the method used for ctDNA detection; and (3) the main findings in the studies. CONCLUSIONS: The studies highlight that the level of ctDNA in RCC appears to be low. Studies using multiple methods for ctDNA detection indicate that tumor-guided analysis improves the ctDNA detection rate and suggest that cell-free methylated DNA immunoprecipitation and high-throughput sequencing may be a very sensitive method for ctDNA detection in RCC. PATIENT SUMMARY: We systematically reviewed the literature to identify all relevant studies investigating circulating tumor DNA in patients with kidney cancer to investigate its use and potential in this highly malignant disease. We found that the level of circulating tumor DNA is low in kidney cancer and that very sensitive methods have to be used for detection in this disease.