Introduction

Though upper tract urothelial carcinoma only accounts for approximately 10% of all urothelial cancers, its often aggressive characteristics mandate explicit diagnosis and treatment.¹

The historical gold standard of treatment with nephroureterectomy often leads to increased morbidity and chronic kidney disease. However, improvements in endoscopic technologies can preclude extirpative treatment and maintain oncologic control in select situations. Specifically, for patients with low-risk disease, renal insufficiency, a functionally solitary kidney, bilateral disease, hereditary malignancy (ie Lynch syndrome) or those who are poor surgical risk, endoscopic management may be preferred. New improvements in endoscopic visibility, access and different ablation modalities may allow for more durable oncologic control in appropriately selected patients and minimize treatment morbidity.

Scope Selection

Fundamentally, endoscopic surgery depends on clear visualization of a body cavity or hollow viscus. Though fiberoptic scopes are more affordable and offer better flexibility, digital scopes provide for improved image resolution and the integration of enhanced imaging strategies (ie narrow band imaging) to improve diagnosis and treatment of upper tract tumors (Fig. 1).² Although no oncologic benefit has been demonstrated from the use of digital over fiberoptic scopes, digital scopes have shown improvements in operative time for endoscopic surgery.^3,4 We further believe they lead to a decreased cognitive workload, allowing for more efficient tumor treatment. There are some limitations to maneuverability of digital scopes and concerns for costs related to breakage; however, newer disposable scopes may mitigate these concerns while optimizing upper tract cancer treatment.

Figure 1. Digital vs fiber optic image quality.

“Although no oncologic benefit has been demonstrated from the use of digital over fiberoptic scopes, digital scopes have shown improvements in operative time for endoscopic surgery.^3,4”

Upper Tract Access

Intraoperatively, starting each case with fluoroscopic imaging (ie a retrograde or antegrade pyelogram) allows for the detection, location and size of any filling defects consistent with the tumor (Fig. 2, a). Ureteral wires for access should be placed and advanced carefully to prevent disturbing urothelium and leading to bleeding that might impair visibility. In some cases, inspecting the distal ureter with a semirigid ureteroscope can help visually rule out distal ureteral tumors if treatment of proximal ureteral or renal lesions is required. For treatment of proximal/renal lesions, we favor the use of an access sheath to 1) improve ease of overall access, 2) lower intrarenal pressures, 3) improve visibility with irrigation and 4) allow for varied instrumentation for biopsy and treatment.⁵ Additionally, there are certain situations that warrant percutaneous access for adequate biopsy and resection of upper tract tumors. For patients with prior urinary diversions, or large tumors that are inadequately treated in retrograde fashion, percutaneous access can provide for a feasible means of tumor resection (Fig. 2, b–d). Depending on the size of the tumor, the tract can be dilated from 10Fr to 30Fr. Larger sheaths allow for placement of larger instruments or resectoscopes for better tumor resection.

Figure 2. a, retrograde pyelogram showing filling defect of left kidney renal pelvis. b, percutaneous access into lower pole calyx. c, toothed grasper for percutaneous removal of tumor. d, tumor removed from renal pelvis.

Selection of Biopsy Tool and Laser Modality

A variety of different instruments have been developed for ureteroscopic biopsy and removal of tumors in the upper tract. Instrument choice should be adapted based on location, size and shape of the tumor. Flat tumors, for example, are best sampled with something similar to a forceps grasper (eg Piranha™, Boston Scientific). Sometimes the angle of instrumentation can be challenging for sampling flat tumors (such as in the ureter) and a brush biopsy can also be performed for diagnosis. Papillary tumors, on the other hand, can be easily removed with a nitinol basket (eg Zero Tip™, Boston Scientific). Larger biopsy instruments, such as the 6Fr BIGopsy^® forceps, have shown effectiveness in getting bigger biopsy specimens, but they require an access sheath for usage and their size limits both visibility and scope flexibility.⁶ Additionally, further diagnostic sensitivity can be enhanced by selective cytology and/or urinary biomarkers as well.

While holmium laser ablation of upper tract tumors has shown good oncologic outcomes, its long wavelength increases the risk for bleeding during ablation and visibility concerns.⁷ Thus, we start with a lower setting of energy (0.3 J) and increase if necessary. We recommend at most 1 J and 10 Hz for ablation to prevent damage to healthy tissue. Hemostasis can be achieved by “defocusing” the laser at the target tissue. Likewise, distance mode can control bleeding, while contact mode may help resect a tumor or cut a stalk.

On the other hand, the continuous, shorter wave of the thulium fiber (ie diode-pumped laser) has decreased tissue penetration and risk of injury to normal tissue by providing more precise vaporization. However, thulium fibers are prone to necrotic tissue adherence to fiber tip, which can obstruct vision and require cleaning during the case.⁸ With the thulium fiber, we recommend settings between 0.3 and 1 J and 10 and 40 Hz for a maximum of 20 W in the kidney, and 0.3 to 0.6 J, and 5 to 15 Hz for a maximum of 4 W in the ureter. It is possible that holmium laser pulsed modulation may achieve similar results. Of note, there also exist ureteroscopic Bugbee electrodes; however, their size, impedance to irrigation and maneuverability limit their use.

Future Practice Considerations

Endoscopic therapy has shown adequate oncologic control in selected patients.⁹ No prospective trials have directly compared endoscopic therapy to the gold standard of nephroureterectomy. However, a prior meta-analysis revealed similar overall and cancer-specific survival for endoscopic compared to extirpative therapy for upper tract urothelial carcinoma.¹⁰ Though the analysis is limited by low-level evidence and trial heterogeneity, these results are reassuring. Another strategy we perform that may mitigate oncologic outcomes for endoscopic treatment includes short-term (ie 6 weeks) surveillance endoscopy to ensure complete tumor ablation. Furthermore, intraluminal agents (ie mitomycin gel, bacillus Calmette-Guérin) may act as adjuncts for endoscopic upper tract tumor treatment for low-risk patients. Though morbidity is overall improved with endoscopic rather than extirpative surgery, endoscopic management is not without complications, which include urinary tract infections, ureteral strictures, need for a ureteral stent, need for recurrent anesthetics and concerns for tumor seeding, among others. Despite this, endoscopic treatment of upper tract urothelial carcinoma has become critical to patient care. Intraoperative decisions that improve diagnosis, visibility, access and treatment should be carefully made to maximize successful tumor treatment.