Feasibility of EGFR Mutation Testing Without Nucleic Acid Extraction in Scraped Cytologic Samples Using the Idylla...

Area of Science:

• Molecular Pathology
• Cytopathology
• Oncology Diagnostics

Background:

• EGFR mutation testing is crucial for guiding lung cancer treatment.
• Current molecular testing often requires nucleic acid extraction, limiting accessibility.
• Cytologic material is frequently the only available sample for analysis.

Purpose of the Study:

• To evaluate the feasibility of EGFR mutation testing on scraped cytologic material using the Idylla platform.
• To assess a simplified workflow without prior nucleic acid extraction.
• To determine the potential for broader access and reduced turnaround times in molecular pathology.

Main Methods:

• Analysis of 30 scraped cytology preparations from 20 patients (9 EGFR-mutated, 11 wild-type).
• Direct transfer of scraped material onto the Idylla cartridge without nucleic acid extraction.
• Comparison with a reference molecular method on corresponding cell blocks.

Main Results:

• Accurate EGFR mutation detection was achieved on scraped cytologic material.
• Three invalid runs (10%) were observed, potentially due to DNA degradation in pleural fluid.
• Three false-negative results (11.11%) occurred in cases with low absolute tumor cellularity.

Conclusions:

• EGFR mutation testing on scraped cytology using the Idylla platform is technically feasible without prior nucleic acid extraction.
• The method offers potential for shorter turnaround times and wider accessibility in routine pathology.
• Caution is advised for specimens with low absolute tumor cellularity due to potential false negatives.