[Predictive immunocytochemistry in non-small cell lung carcinoma]

Area of Science:

• Oncology
• Pathology
• Biomarker Discovery

Background:

• Predictive immunochemistry is vital for advanced non-small cell lung cancer (NSCLC) biomarker testing.
• Formalin-fixed, paraffin-embedded (FFPE) tissue is standard for PD-L1, ALK, ROS1, and NTRK testing.
• Cytology specimens are critical as 40% of NSCLC are diagnosed via cytology alone, yet IHC assays lack validation for these samples.

Purpose of the Study:

• To review preanalytical, analytical, and postanalytical factors influencing immunocytochemistry (ICC) results.
• To summarize published data on predictive ICC for PD-L1, ALK, and ROS1 in NSCLC.
• To highlight the importance and reliability of ICC on non-FFPE cell block cytology specimens.

Main Methods:

• Review of preanalytical, analytical, and postanalytical aspects of ICC.
• Summary of published data on predictive ICC for key NSCLC biomarkers.
• Discussion on the validation and optimization of ICC protocols for cytology specimens.

Main Results:

• FFPE cell blocks (CB) allow for ICC using standardized histology protocols.
• Non-CB cytology specimens require rigorous, cytology-specific ICC protocol optimization and validation.
• Optimized ICC on Papanicolaou-stained cytology is robust and reliable for predictive biomarker testing.

Conclusions:

• Predictive ICC on non-CB cytology specimens is a robust and reliable method for NSCLC biomarker testing.
• Underutilization of cytology material for biomarker testing risks patient harm due to repeat sampling.
• Standardized protocols and quality control are essential for accurate ICC on cytology specimens.