Our preliminary study showed that percutaneous laser ablation had much less surgery time and hospital stay than radical nephroureterectomy with similar renal function during the follow-up. The HR of DFS in standard radical nephroureterectomy (group II) was lower than that in patients who were treated with percutaneous laser ablation laser treatment (group I), but it is not statistically significant. This may be due to the small sample size, which lacks sufficient statistical power to detect significant differences. Both the unadjusted K–M survival curve and the Cox regression-adjusted survival curve suggest that percutaneous laser ablation did not match the oncologic outcomes of radical nephroureterectomy, but further data validation is required. But from the preliminary data, we can calculate that to detect the statistically significance between the two group we need at least 72 events with 5 years follow-up time. The total sample size should be more than 200 patients. It is unrealistic for a single center to recruit such a large number of pelvic tumor patients. This study suggests that endoscopic laser treatment is significantly less invasive, with less blood loss and shorter hospital stays, but it may have an impact on oncologic outcomes. Given the small sample size, further research is essential to confirm these findings.

Some of the patients in this study did not conform to standard current guidelines regarding tumor size, grading, and stage. This was unavoidable for urologists who treated these patients with a solitary kidney, concurrent bilateral malignancy, renal insufficiency, concomitant medical conditions, personal concerns, or octogenarians. These conditions were prohibitive for a major operation, such as nephroureterectomy [13]. In certain cases, particularly when radical nephroureterectomy is not feasible, percutaneous laser ablation remains a safe and effective treatment option, especially for patients with compromised kidney function or those who refuse nephrectomy, considering the limited alternatives available. The European Association of Urology guideline has already approved recommendations to renal pelvis carcinoma patients with carefully selected characteristics [14].

Retrograde flexible ureteroscopy with laser treatment is a choice for treatment of some renal tumor carcinomas [2]. Unfortunately, 500-μm lasers cannot be applied via a ureteroscope with a small lumen, which is much more effective in tissue vaporization [15]. Therefore, the 200 μm holmium laser applied in flexible ureteroscopy is not sufficiently effective to carry out tumor vaporization for larger tumors [4]. In our clinical practice, we first carried out this nephron-sparing procedure in patients with special conditions, such as those with a congenital solitary kidney or functional solitary kidney, or those unwilling to receive radical nephrectomy. Local re-occurrence or the metastasis rate is still high during postoperative follow-up in these patients. In recent years, using evidence-based medicine, many guidelines have recommended strict criteria for kidney-sparing surgery in patients with UTUC [16]. These include a unifocal tumor, a tumor < 1 cm, a low-grade tumor, no evidence of an infiltrative lesion on computed tomography, and understanding of strict follow-up after surgery [6]. A laser should usually be used for endoscopic treatment and flexible ureteroscopy is preferred for rigid ureteroscopy, regardless of whether the tumor is in the renal pelvis or in the distal, mid, or proximal ureter [17, 18].

In previous reports, most of these procedures were finished by laser via flexible ureteroscopy. This retrograde pathway is often affected by the condition of the ureter and a large portion of patients require placement of the ureteral sheath before a second-stage treatment [9]. When using a flexible ureteroscope, several factors, such as a narrow and confined space, make tumor ablation difficult and slow, and increase the chance of infection. In addition, tumors are sometimes not accessible, especially for tumors at the inferior calices [10]. With wide application of PC, it is no longer only suitable for kidney stone treatment. The percutaneous approach has many advantages, including a wide lumen space, sufficient liquid outflow, and accessibility to target calices. PC can provide a better view, and more importantly, it can lower renal pelvic pressure by free liquid outflow and significantly reduce occurrence of postoperative sepsis compared with flexible ureteroscopy [19]. In addition, under percutaneous access, a wider aperture and more powerful laser for vaporization can be applied to achieve a more effective ablation result [12]. Furthermore, bladder chemotherapy can also be applied via a renal fistula tube after this procedure. After removal of the fistula, bladder instillation therapy can be performed when a ureteral double-J stent remains [13]. However, this is still controversy regarding effectiveness of bladder instillation in tumor control.

There have been no previous reports on patients with UCC who refused radical nephroureterectomy, either because of personal concerns or because of a solitary function kidney, and who had percutaneous endoscopy laser ablation instead. In our study, we compared patients with renal pelvic carcinoma who were treated with laser ablation under percutaneous endoscopy and those who received standard radical nephroureterectomy. To the best of our knowledge, this study is the first prospective cohort study to compare these treatments in Chinese patients with UTUC.

Several limitations of this study warrant consideration. First, the sample size was limited to 30 patients, which may compromise the robustness of the statistical analyses, particularly since some treatment comparisons did not achieve statistical significance. Although percutaneous laser ablation demonstrated benefits in terms of reduced surgical duration and shorter hospital stays, the small sample size may not adequately capture the true differences between the two treatment modalities. Second, the follow-up period was relatively brief, with an average duration of 34 months. While no local or systemic metastasis was detected during this period, short-term data are insufficient to fully assess the long-term effects of the treatments. Given the potential for renal pelvic carcinoma to exhibit a prolonged latency period, extended follow-up studies are necessary to more accurately evaluate the long-term outcomes, especially concerning recurrence and metastasis rates. Lastly, the study did not comprehensively account for other potential influencing factors, such as patients’ quality of life, which could significantly affect overall treatment outcomes. Future studies should incorporate additional clinical indicators, especially quality of life measures, to more comprehensively evaluate the overall efficacy of the two treatment options.