Tissue polypeptide antigen as a non-invasive bladder Cancer biomarker

Area of Science:

• Biochemistry
• Oncology
• Clinical Diagnostics

Background:

• Tissue Polypeptide Antigen (TPA) is a non-invasive biomarker derived from cytokeratins 8, 18, and 19.
• TPA shows potential for non-invasive bladder cancer surveillance, but standardization challenges hinder clinical use.

Purpose of the Study:

• To review the molecular biology of TPA and its clinical laboratory practice.
• To emphasize analytical standardization, preanalytical harmonization, and diagnostic algorithms for TPA.

Main Methods:

• Narrative review focusing on TPA's analytical and clinical aspects.
• Analysis of TPA performance in non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC).

Main Results:

• Urinary TPA demonstrates high sensitivity (80-85%) and specificity (97%) in optimized protocols for high-risk NMIBC.
• Monoclonal chemiluminescent assays show low intra-assay variation (<5%) but significant inter-method bias (20-30%).
• TPA integrated with cytology and immunocytochemistry yields a diagnostic area under the curve >0.90.

Conclusions:

• TPA is valuable for compartment-specific surveillance, particularly in multi-marker algorithms, rather than as a standalone test.
• Standardized preanalytical operations (IFCC-aligned), laboratory-specific cutoffs, and external quality assurance are crucial for clinical implementation.
• Further research on cost-effectiveness and reducing TPA-directed cystoscopies is needed.