[Molecular diagnostics of cytological specimens]

Area of Science:

• Molecular Pathology
• Oncology
• Cytopathology

Background:

• Targeted therapies for lung carcinomas with specific genetic alterations (ALK, BRAF, EGFR) require molecular pathological testing.
• Biopsy samples often yield insufficient tumor content for molecular analyses like PCR-based examinations or FISH.
• Limited sample material poses a challenge for comprehensive molecular diagnostics in lung cancer.

Purpose of the Study:

• To evaluate the utility of cytological preparations for molecular genetic testing in lung cancer.
• To determine the success rates of NGS and FISH analyses on cytological samples.
• To establish comprehensive diagnostics for lung cancer using limited starting material and avoid re-biopsies.

Main Methods:

• Cytological preparations (e.g., brush smears, needle aspirates, effusions) were utilized after morphological analysis and confirmatory diagnosis.
• Cytopathologists identified and marked tumor cell areas for DNA extraction or FISH analysis.
• Stained sections were destained prior to hybridization for FISH analysis; NGS and FISH were performed on these preparations.

Main Results:

• A total of 1711 next-generation sequencing (NGS) and FISH analyses were performed on cytological preparations between 2016 and July 2019.
• The success rate for NGS examinations was 85.9%.
• The success rate for FISH analyses was 82.8%.

Conclusions:

• Cytological preparations are a viable alternative for molecular testing when biopsy material is limited.
• This method allows for comprehensive molecular diagnostics, including NGS and FISH, thereby avoiding the need for re-biopsies.
• Successful molecular profiling can be achieved even with small sample sizes, facilitating targeted therapy decisions.