Closing the diagnostic gap in upper tract urothelial carcinoma: the emerging role of urinary multiplex biomarkers

Upper tract urothelial carcinoma (UTUC) is a rare malignancy, accounting for 5–10% of all urothelial cancers, yet it poses substantial diagnostic challenges (1). Current evaluation relies on imaging, urine cytology, and ureteroscopic assessment with biopsy (1,2). However, each modality has important limitations: imaging lacks sensitivity for small or flat lesions, while voided urine cytology, despite high specificity, performs poorly in low-grade disease (2,3).

Consequently, diagnosis often depends on invasive procedures that are technically demanding, costly, and associated with morbidity (2,4). Importantly, diagnostic uncertainty has direct clinical implications, as both delayed detection and overtreatment—particularly in a disease where radical nephroureterectomy remains common—carry significant risks (5,6).

These limitations highlight an unmet need for accurate, noninvasive diagnostic tools. In this context, urinary biomarker-based approaches, particularly multiplex assays, have emerged as a promising strategy to improve diagnostic accuracy while reducing reliance on invasive procedures (7).

In their study, Fujita et al. evaluated the diagnostic performance of the Oncuria-Detect multiplex immunoassay, a urine-based test quantifying a panel of 10 protein biomarkers, in patients undergoing evaluation for suspected UTUC (8). In a multicenter case–control design, 60 patients with histologically confirmed UTUC were compared with 60 matched controls with a negative hematuria workup.

Oncuria-Detect achieved an overall sensitivity of 92–93% and a specificity of 55–58%, with a negative predictive value of up to 89% and an area under the curve of 0.77. Notably, assay sensitivity remained high across clinically relevant subgroups, including low-grade and noninvasive tumors. In comparison, voided urine cytology demonstrated substantially lower sensitivity but high specificity, consistent with its known diagnostic profile (2).

These findings suggest that Oncuria-Detect may offer potential utility as a noninvasive rule-out test in the diagnostic workup of UTUC.

A key strength of this study lies in its focus on an important clinical gap in UTUC diagnostics, namely the limited sensitivity of urine cytology, particularly for low-grade disease. In this context, the consistently high sensitivity of the Oncuria-Detect assay across tumor grades and stages represents a notable advance, as it addresses one of the most relevant shortcomings of current noninvasive approaches.

From a biological perspective, the use of a multiplex protein-based assay is conceptually compelling. By capturing a panel of secreted tumor-associated biomarkers rather than relying on exfoliated malignant cells, this approach may overcome inherent limitations of cytology-based diagnostics. Moreover, the use of a multiplex panel more adequately reflects the biological heterogeneity of urothelial carcinoma than single-marker approaches, potentially allowing for more robust detection across different tumor phenotypes (9).

Despite these strengths, several limitations warrant careful consideration. First, the retrospective case–control design introduces an inherent risk of spectrum bias and may lead to an overestimation of diagnostic performance. The equal distribution of cases and controls does not reflect real-world disease prevalence, thereby limiting the interpretability of predictive values and their applicability to clinical practice.

Second, these design-related considerations are particularly relevant when interpreting the balance between sensitivity and specificity. Although the assay demonstrates high sensitivity, its modest specificity of approximately 55% may limit its standalone clinical utility. In routine practice, a positive test result would typically prompt further diagnostic evaluation, most notably ureteroscopic assessment with biopsy (2). A high false-positive rate could therefore translate into an increased number of unnecessary invasive procedures, with associated costs, patient burden, and procedural risks. Thus, while the assay may be well suited as a rule-out test, its role as a decision-making tool remains to be more clearly defined.

Third, comparisons with established diagnostic modalities should be interpreted with caution. Cytology data were only available in a subset of patients, and selective upper tract cytology was inconsistently performed, precluding a robust head-to-head evaluation.

In addition, several factors relevant to real-world implementation remain insufficiently addressed. Pre-analytical variability across participating centers, as well as potential confounders such as renal function or inflammatory conditions affecting urinary protein levels, may have influenced assay performance, particularly specificity (10,11).

Finally, the absence of prospective validation and external real-world cohorts limits conclusions regarding robustness, reproducibility, and clinical integration. More broadly, this challenge is not unique to Oncuria-Detect but reflects a common limitation of urine-based biomarkers, many of which have not yet been adequately evaluated within prospective, clinically integrated decision-making algorithms (12). At present, the role of the assay within established diagnostic pathways remains to be more clearly defined.

From a clinical perspective, the findings suggest that Oncuria-Detect may have potential utility as a noninvasive adjunct in the diagnostic workup of patients with suspected UTUC. In particular, its high sensitivity and negative predictive value indicate that the assay could be useful in ruling out disease in selected clinical scenarios, thereby complementing imaging-based evaluation and potentially reducing the number of unnecessary invasive procedures.

However, given its limited specificity, the test is unlikely to function as a standalone decision-making tool. In current practice, a positive result would require confirmation through endoscopic assessment and histological verification, and should therefore be interpreted within the broader clinical context (2).

A more plausible role may lie in its integration as a triage tool, helping to refine risk stratification and guide the need for further invasive diagnostics. For example, in patients with equivocal imaging findings or inconclusive cytology, a negative test result could support a more conservative approach, whereas a positive result might reinforce the indication for ureteroscopic evaluation.

The clinical value of such assays will depend on their ability to improve diagnostic pathways in a meaningful way—either by safely reducing unnecessary invasive procedures or by facilitating earlier and more accurate detection. Whether Oncuria-Detect can achieve this in routine practice remains to be demonstrated in prospective, clinically embedded studies.

Future studies should focus on prospective validation of Oncuria-Detect in real-world clinical settings, ideally within well-defined diagnostic algorithms for patients with suspected UTUC. In particular, its incremental value beyond established modalities such as imaging and cytology requires further clarification.

Moreover, integration into risk-adapted diagnostic pathways, potentially in combination with other clinical and molecular parameters, may help to better define its role in guiding patient selection for invasive procedures. Ultimately, demonstrating a tangible impact on clinical decision-making and patient outcomes will be essential to support broader adoption.

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.