Clinical Report: INSM1 Expression in Mixed Urothelial and Small-Cell Carcinoma

Overview

This study evaluates the expression of INSM1 in mixed urothelial carcinoma and small-cell carcinoma of the renal pelvis, demonstrating its high sensitivity compared to traditional neuroendocrine markers.

Background

Mixed urothelial carcinoma and small-cell carcinoma of the renal pelvis are rare but significant malignancies that require accurate diagnosis for effective treatment. The study highlights the need for precise histopathological recognition of these tumors due to their aggressive nature and distinct treatment pathways.

Data Highlights

Key Findings

• INSM1 demonstrated 96.3% sensitivity in the SmCC compartment.
• INSM1 was significantly more sensitive than synaptophysin and chromogranin A.
• CK7 and GATA3 were exclusively retained in the UC compartment.
• The median Ki-67 index was higher in SmCC (76%) compared to UC (24%).
• Higher INSM1 H-score was associated with adverse overall survival.
• Adjuvant chemotherapy was linked to reduced mortality risk.

Clinical Implications

Understanding the expression patterns of neuroendocrine markers can inform prognostic assessments and therapeutic strategies.

Conclusion

INSM1 is a sensitive marker for the SmCC component in mixed tumors. Further research in larger cohorts is necessary to validate these findings.

Related Resources & Content

1. Author(s)/Org, Source, Year -- Title
2. Frontiers in Oncology, 2026 -- POU2F3-positive small cell neuroendocrine carcinoma of the urinary tract: a clinicopathological analysis of five cases
3. CAP, 2025 -- Current Cancer Protocols for Ureter/Renal Pelvis Resections
4. PubMed, 2020 -- Adjuvant chemotherapy in upper tract urothelial carcinoma (the POUT trial)
5. The ASCO Post — Marker for Distinguishing Renal Cell Carcinoma From Benign Renal Masses
6. Assessment of Diagnostic Nomograms Utilizing CE–MS Urinary Biomarkers for Identifying Clinically Relevant Prostate Cancer
7. https://documents.cap.org/documents/New-Cancer-Protocols-March-2025/UreterRenalPelvis.Res_2.4.0.0.REL.CAPCP.pdf
8. Adjuvant chemotherapy in upper tract urothelial carcinoma (the POUT trial): a phase 3, open-label, randomised controlled trial - PubMed
9. Table S8.2  Major pathological features and prognosis of neuroendocrine tumour (NET) at various anatomical sitesa (continued on next page)