# Laser Energy Application in Endoscopic Kidney-Sparing Surgery for Upper Tract Urothelial Carcinoma: A Systematic Review of Oncological Outcomes and Surgical Complications

## TL;DR

This review examines how different laser technologies used in kidney-preserving surgery for upper urinary tract cancer affect cancer recurrence and complications.

## Contribution

The study systematically compares laser platforms in endoscopic kidney-sparing surgery for UTUC, highlighting gaps in evidence and trends in outcomes.

## Key findings

- Recurrence after eKSS is common across all laser types.
- Thulium-based lasers may show lower progression rates compared to holmium:YAG lasers.
- Major complications are rare, but evidence is limited by study design and heterogeneity.

## Abstract

Endoscopic kidney-sparing surgery (eKSS) has become an established treatment option for selected patients with upper tract urothelial carcinoma (UTUC), aiming to preserve renal function while maintaining acceptable oncological control. Laser energy represents the cornerstone of endoscopic tumor ablation, yet multiple laser platforms with different physical properties are currently available, and their relative impact on oncological and safety outcomes remains unclear. This systematic review summarizes the available clinical evidence on laser-based endoscopic management of UTUC, focusing on recurrence, progression, conversion to radical nephroureterectomy, and treatment-related complications. Overall, recurrence after eKSS remains frequent across all laser technologies, whereas progression and major complications are uncommon. Thulium-based lasers and thulium fiber laser (TFL) appear to have lower progression and radical surgery rates compared with holmium:YAG in descriptive analyses, although follow-up is generally shorter and evidence is limited by study heterogeneity and retrospective designs. Current data do not support a definitive superiority of one laser technology over another. Treatment selection should therefore be guided by tumor characteristics, surgeon expertise, and institutional experience. Well-designed prospective and comparative studies are urgently needed to clarify whether specific laser platforms translate into meaningful oncological or safety advantages in kidney-sparing UTUC management.

Background: Endoscopic kidney-sparing surgery (eKSS) is increasingly adopted for the management of selected patients with upper tract urothelial carcinoma (UTUC). Laser energy is central to tumor ablation during eKSS; however, multiple laser platforms with distinct physical and thermal properties are currently available, and their comparative oncological and safety profiles remain poorly defined. This systematic review aims to summarize the available evidence on oncological outcomes and perioperative complications associated with laser-based endoscopic treatment of UTUC and to explore potential differences according to laser technology. Methods: A systematic literature search identified 25 eligible studies published between 1997 and 2024, including 1344 patients treated with laser-assisted eKSS. All included studies were non-randomized, predominantly retrospective, and characterized by moderate-to-serious risk of bias. Holmium:YAG, Thulium:YAG (thu:YAG, continuous-wave and pulsed), thulium fiber laser (TFL), Neodimio:YAG (Nd:YAG), diode lasers, and combination platforms were reported. Results: Ipsilateral upper tract recurrence was common across all laser categories, with weighted proportions ranging approximately from 27% to 52% and substantial inter-study heterogeneity. Progression and conversion to radical nephroureterectomy (RNU) were relatively infrequent overall, with numerically weighted proportions observed in thu:YAG-based cohorts. Major complications (Clavien–Dindo ≥ III) were rare across all laser technologies, although a trend toward a higher weighted proportions was observed in Ho:YAG- and Nd:YAG-based series. Minor complications were more frequently reported and highly heterogeneous. Conclusions: Available evidence supporting laser selection in endoscopic kidney-sparing management of UTUC is limited and largely descriptive. Thulium:YAG and TFL platforms seem to demonstrate encouraging trends toward lower progression and conversion to-radical-nephroureterectomy rates; however, these findings are derived from heterogeneous, non-comparative studies with limited follow-up. No standard laser platform can currently be recommended over others based on existing data. Prospective, comparative, and methodologically robust studies are required to determine whether laser technologies confer clinically meaningful advantages in oncological control or safety for UTUC treated with eKSS.