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Diagnostic and Predictive Immunocytochemistry in Lung Cancer
Deepali Jain1, Shraddhanjali Satapathy1, Lukas Bubendorf2
1Department of Pathology, All India Institute of Medical Sciences (AIIMS), New Delhi, India.
Insights
Immunocytochemistry (ICC) is vital for lung cancer diagnosis, offering reliable results on various cytology samples. Validation ensures accuracy, but predictive markers like PD-L1 may require cell blocks or biopsies.
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.
Background:
Immunocytochemistry (ICC) is suitable for use on a range of cytology preparations, such as cell blocks, air-dried slides, ethanol-fixed slides, direct smears, cytospins, and liquid-based cytology (LBC) samples. However, it must be standardized against the gold standard of formalin-fixed paraffin-embedded tissues with adequate number of positive and negative controls. The role of ICC in lung cancer is crucial, as most lung cancer specimens are cytology samples. Accurate diagnosis and testing of certain biomarkers rely heavily on both diagnostic and predictive ICC.
Summary:
Key ICC markers important in lung cancer include, but are not limited to, diagnostic ICCs such as TTF-1, p40, Napsin A, and p63, as well as predictive ICCs like ALK, ROS-1, PD-L1, and NTRK.
Key Messages:
With proper validation, immunocytochemistry for lung cancer can be effectively performed on direct smears, cytospins, and other specimens, even when resources for preparing cell blocks are unavailable. This is particularly true for diagnostic antibodies, but it is important to exercise caution with predictive ICC. Nonetheless, a low threshold for molecular testing should be maintained. PD-L1 ICC can be challenging and should ideally be performed on formalin-fixed cell blocks or biopsies when available.
Background:
Immunocytochemistry (ICC) is suitable for use on a range of cytology preparations, such as cell blocks, air-dried slides, ethanol-fixed slides, direct smears, cytospins, and liquid-based cytology (LBC) samples. However, it must be standardized against the gold standard of formalin-fixed paraffin-embedded tissues with adequate number of positive and negative controls. The role of ICC in lung cancer is crucial, as most lung cancer specimens are cytology samples. Accurate diagnosis and testing of certain biomarkers rely heavily on both diagnostic and predictive ICC.
Summary:
Key ICC markers important in lung cancer include, but are not limited to, diagnostic ICCs such as TTF-1, p40, Napsin A, and p63, as well as predictive ICCs like ALK, ROS-1, PD-L1, and NTRK.
Key Messages:
With proper validation, immunocytochemistry for lung cancer can be effectively performed on direct smears, cytospins, and other specimens, even when resources for preparing cell blocks are unavailable. This is particularly true for diagnostic antibodies, but it is important to exercise caution with predictive ICC. Nonetheless, a low threshold for molecular testing should be maintained. PD-L1 ICC can be challenging and should ideally be performed on formalin-fixed cell blocks or biopsies when available.
