Positioning the role of urine cytology within the diagnostic pathway for UTUC: supportive but inconclusive

Purpose: With the introduction of kidney-sparing surgery (KSS) for low-risk Upper Tract Urothelial Carcinoma (UTUC), correct risk-stratification has become crucial. High-grade cytology is one of the decisive variables to stratify a tumor as high-risk. To position the role of urine cytology in the diagnostic pathway of UTUC patients, we evaluated the accuracy of urine cytology by comparing the outcomes with histopathology. Method: Patients with UTUC evaluated between 2010 and 2020, and diagnosed by imaging, cytology and histopathology were selected. Descriptive statistics were used to compare cytology with histopathological outcomes using crosstabs. Clinical performance characteristics of cytology were determined for the presence of a malignancy. Results: This study included 176 patients with confirmed histopathological UTUC. Concordance between cytology and biopsy results was found in 14.8% of low-grade tumors and 16.8% of high-grade tumors. Comparing cytology with radical nephroureterectomy (RNU) specimens revealed concordance rates of 1.6% for low-grade tumors and 22.9% for high-grade tumors. Notably, 51.1% of urine cytology results were false negative. Sensitivity for detecting high-grade and low-grade tumors with a positive urine cytology was 56.6% and 52.6%, respectively, with specificities of 54.8% and 37.2%. Conclusion: In the current study, cytology appears to exhibit limited reliability when used as a sole diagnostic tool for assessing tumor grade and consequently risk stratification. It is imperative to recognize these limitations, optimize urine sampling techniques, and leverage a combination of diverse diagnostic methods for the most effective and individualized treatment decision-making.