Emerging Role of <scp>ctDNA</scp> Fragmentomics and Epigenetic Signatures in the Early Detection, Minimal Residual Disease Assessment, and Precision Monitoring of Renal Cell Carcinoma

Renal cell carcinoma (RCC) presents a significant global health challenge, with a substantial proportion of patients diagnosed with advanced or metastatic disease due to the limitations of current diagnostic imaging and the lack of validated non-invasive biomarkers. These conventional methods, including computed tomography and magnetic resonance imaging, often lack the sensitivity and specificity to differentiate benign from malignant small renal masses reliably or to detect minimal residual disease (MRD) post-treatment. This review explores the transformative potential of liquid biopsy, explicitly focusing on circulating tumour DNA (ctDNA) fragmentomics and epigenetic signatures, to overcome these clinical hurdles. This review also explores how the analysis of ctDNA fragmentation patterns-such as size distribution, end motifs, and nucleosome footprints-provides a mutation-independent method to enhance RCC detection, even in low-shedding tumours. Concurrently, RCC-specific epigenetic alterations, particularly DNA methylation profiles, offer particular biomarkers for early detection, tumour classification, and prognostication. This Review examines evidence that integrating these multi-analyte approaches-combining fragmentomic and epigenetic data-synergistically improves diagnostic accuracy, enables sensitive MRD assessment, and allows precision monitoring of treatment response and tumour evolution. Despite existing technical and biological challenges, the convergence of ctDNA fragmentomics and epigenetic profiling heralds a new era for the non-invasive, dynamic, and personalised management of RCC, promising to improve patient outcomes through earlier intervention and tailored therapeutic strategies.