Aspiration Cytology Is a Resource for Molecular Profiling

Archived and stained fine needle aspirate smears can be used for clinical molecular diagnosis and profiling.

DNA can be extracted from aspirate smears stained with Papanicolau (Pap) and Diff-Quick (DQ) stains that were prepared by technicians in a single laboratory according to standard procedure, mounted with a glass coverslips, and stored at room temperature under typical pathology archive conditions.

In a study performed at the National Cancer Institute, (Bethesda, MD, USA), 57 fine-needle aspiration cytopathology (FNAC) samples were examined for aberration detection on high-resolution comparative genomic hybridization array, DNA methylation, and single nucleotide polymorphism genotyping platforms. The samples were from patients with suspected small cell lung cancer (SCLC), metastatic lymph node cancer, and/or primary lymphoma.

Cellular material is collected by scraping the entire slide with a razor blade; this is facilitated by wetting the slide with a small amount of about 20 µL of lysis buffer, which helps the material form a clump during scraping. The average DNA yield per slide in this study was 7.4 µg (range: 0.1 µg to 27.9 µg). Unequivocal genomic structural aberrations were identified in 44 of 46 malignant smears. Even the degraded archival Pap smear DNA showed similar structural aberrations matched to DQ samples on Agilent array comparative genomic hybridization (Agilent; Santa Clara, CA, USA) and Infinium genotyping (Illumina; San Diego, CA, USA), although with greater background noise.

The authors of the study concluded, "Cytopathology specimens are an excellent potential source of patient materials for clinical molecular profiling, including retrospective genomic analyses and prospective sample collection for individualized therapy or eligibility review for clinical trial enrollment. FNAC samples up to 16 years old yielded copious quantities of genomic DNA suitable for high-resolution genomic and epigenomic profiling". The study was published in November 2010, in the Journal of Molecular Diagnostics.

Related Links:
National Cancer Institute
Agilent
Illumina