Table 2.

Current clinical boundaries of kidney-sparing surgery in UTUC.

Domain	Current position	Why it matters for KSS	Representative refs
Risk framework	Integrated clinicopathologic stratification; no molecular biomarker is validated for routine use yet.	Supports the manuscript premise that KSS depends on composite risk estimation rather than a single test.	(8–10)
Low-risk disease	KSS is guideline-supported when findings are concordantly favorable and close surveillance is feasible.	Defines the clearest evidence-based space for organ-preserving management.	(8, 9, 33)
High-risk disease	RNU remains the reference treatment for most high-risk nonmetastatic UTUC.	Frames the threshold that liquid biopsy must challenge only cautiously.	(8–10)
Imperative indications	Renal preservation may be prioritized in solitary kidney, bilateral disease, or chronic kidney disease.	Explains why better biologic triage matters even more when nephron loss has systemic consequences.	(11, 15, 16)
Segmental ureterectomy	A kidney-sparing option particularly relevant for selected ureteral tumours with favorable anatomy.	Illustrates that KSS is a strategy with multiple modalities, not endoscopy alone.	(11, 12, 32)
Chemoablation/focal therapy	UGN-101 and focal ablative approaches expand the KSS toolbox in selected low-grade disease.	Increases the need for accurate patient selection before conservative treatment.	(13, 14, 34)
Surveillance burden	KSS trades extirpation for a longer and more intensive follow-up pathway.	Strengthens the rationale for biomarkers that can refine both upfront selection and later surveillance.	(15, 31, 37)

KSS, kidney-sparing surgery; RNU, radical nephroureterectomy; URS, ureteroscopy; CTU, computed tomography urography; ctDNA, circulating tumor DNA; cfDNA, cell-free DNA; MRD, molecular residual disease; NOC, non–organ-confined; CNV, copy-number variation.