Adequacy of core needle biopsy specimens and fine-needle aspirates for molecular testing of lung adenocarcinomas

Area of Science:

• Oncology
• Pathology
• Molecular Diagnostics

Background:

• Molecular testing for EGFR mutations and ALK translocations in lung adenocarcinoma is crucial for guiding targeted therapy with tyrosine kinase inhibitors.
• The suitability of different biopsy methods for obtaining adequate tissue for this molecular testing is an important clinical consideration.

Purpose of the Study:

• To compare the suitability of transthoracic computed tomography-guided core needle biopsy (CNB) and fine-needle aspiration (FNA) specimens for molecular testing in lung adenocarcinomas.
• To identify factors influencing the adequacy of biopsy specimens for EGFR, KRAS, and ALK testing.

Main Methods:

• A retrospective analysis of 52 CNB and 120 FNA specimens collected over 2 years.
• Determination of the percentage of specimens with sufficient paraffin-embedded tumor tissue for molecular testing (EGFR, KRAS, ALK).
• Correlation of sample sufficiency with biopsy method, tumor size, operator, pathologist assessment, and number of FNA passes.

Main Results:

• CNB specimens yielded a significantly higher proportion of samples sufficient for molecular testing compared to FNA specimens (67% vs 46%; P = .007).
• One operator demonstrated a significantly higher success rate in obtaining sufficient FNA specimens.
• FNA sample sufficiency was correlated with tumor size (P = .015) but not the operator.

Conclusions:

• CNB specimens are more likely than FNA specimens to provide adequate tissue for molecular testing of lung cancer when using paraffin-embedded tissue.
• The adequacy of FNA specimens for molecular testing is dependent on tumor size and the skill of the individual performing the biopsy.