Diagnostic and Predictive Immunocytochemistry in Lung Cancer

Area of Science:

• Cytopathology
• Oncology
• Biomarker Analysis

Background:

• Immunocytochemistry (ICC) is applicable to diverse cytology specimens, including cell blocks, smears, and liquid-based cytology (LBC).
• Standardization against formalin-fixed paraffin-embedded tissues with appropriate controls is essential for ICC reliability.
• ICC plays a critical role in lung cancer diagnosis and biomarker assessment, as cytology samples are common.

Purpose of the Study:

• To evaluate the utility and standardization of immunocytochemistry (ICC) in lung cancer diagnosis.
• To identify key diagnostic and predictive ICC markers for lung cancer.
• To provide guidance on performing ICC on various cytology specimens.

Main Methods:

• Review of immunocytochemistry techniques and applications in lung cancer cytology.
• Identification and categorization of essential diagnostic and predictive ICC markers.
• Assessment of ICC performance on different cytology sample types.

Main Results:

• Key diagnostic ICC markers include TTF-1, p40, Napsin A, and p63.
• Important predictive ICC markers are ALK, ROS-1, PD-L1, and NTRK.
• ICC can be effectively performed on direct smears and cytospins with proper validation, though PD-L1 testing may necessitate cell blocks or biopsies.

Conclusions:

• ICC is a crucial tool for lung cancer diagnosis and biomarker testing on cytology specimens.
• Validated ICC protocols enable accurate results on various sample types, even without cell blocks.
• Caution is advised for predictive ICC, and molecular testing should be readily considered, especially for challenging markers like PD-L1.