Real-Time Tumor Grading in UTUC Using Confocal Laser Endomicroscopy

Overview

This study validates confocal laser endomicroscopy (CLE) criteria for grading upper tract urothelial carcinoma (UTUC) and introduces a scoring system to improve real-time tumor grading accuracy. CLE demonstrated potential for intraoperative risk stratification, addressing limitations of ureteroscopic biopsies.

Background

Upper tract urothelial carcinoma (UTUC) requires accurate risk stratification to guide treatment, with low-risk tumors treated conservatively and high-risk tumors requiring radical surgery. Histopathologic tumor grade is crucial for this stratification, but ureteroscopic biopsies often yield discordant or non-diagnostic results. Confocal laser endomicroscopy (CLE) offers real-time imaging and has been validated for bladder urothelial carcinoma but requires validation for UTUC due to anatomical and technical differences.

Data Highlights

The study used a 2.7 Fr Uroflex-B CLE probe with a 320 µm field of view and 3.5 µm lateral resolution at 40-70 µm depth. CLE imaging was performed on visible UTUC lesions during ureteroscopy, followed by biopsy for histopathologic grading. Diagnostic accuracy metrics such as sensitivity, specificity, positive predictive value, and negative predictive value were calculated comparing CLE grading to biopsy results. Inter-rater agreement was assessed with a threshold of 80% agreement for reliability.

Key Findings

• The proposed CLE criteria for bladder urothelial carcinoma were applicable to papillary UTUC but required validation due to differences in probe size and imaging characteristics.
• CLE enabled real-time grading of UTUC lesions with diagnostic accuracy comparable to histopathologic biopsy, potentially reducing non-diagnostic rates.
• Inter-rater agreement for CLE criteria and grading was evaluated, supporting reproducibility of CLE-based assessment.
• A novel CLE scoring system was proposed based on the criteria with the highest diagnostic potential to standardize UTUC grading intraoperatively.
• Non-diagnostic CLE recordings were identified and quantified, emphasizing the need for quality control in CLE imaging.

Clinical Implications

CLE offers a promising adjunct to ureteroscopic biopsy by providing immediate tumor grade assessment during endoscopy, which may improve patient selection for kidney-sparing treatments. The proposed scoring system facilitates standardized interpretation of CLE images, potentially enhancing diagnostic confidence and guiding intraoperative decision-making. Adoption of CLE could reduce delays and inaccuracies associated with traditional biopsy-based grading.

Conclusion

This study validates CLE criteria for UTUC grading and introduces a scoring system that enhances real-time tumor assessment. CLE has the potential to improve risk stratification and treatment planning in UTUC by providing reliable intraoperative histologic information.

References

1. van der Pol et al. 2024 -- Real-Time Tumor Grading in Upper Tract Urothelial Carcinoma Using Confocal Laser Endomicroscopy