{Reference Type}: Journal Article
{Title}: Assessment of cellularity, genomic DNA yields, and technical platforms for BRAF mutational testing in thyroid fine-needle aspirate samples.
{Author}: Dyhdalo K;Macnamara S;Brainard J;Underwood D;Tubbs R;Yang B;
{Journal}: Cancer Cytopathol
{Volume}: 122
{Issue}: 2
{Year}: Feb 2014
{Factor}: 4.264
{DOI}: 10.1002/cncy.21356
{Abstract}: <B>BACKGROUND: </B>BRAF mutation V600E (substitution Val600Glu) is a molecular signature for papillary thyroid carcinoma (PTC). Testing for BRAF mutation is clinically useful in providing prognostic prediction and facilitating accurate diagnosis of PTC in thyroid fine-needle aspirate (FNA) samples.<BR><B>METHODS: </B>This study assessed the correlation of cellularity with DNA yield and compared 2 technical platforms with different sensitivities in detection of BRAF mutation in cytologic specimens. Cellularity was evaluated based on groups of 10+ cells on a ThinPrep slide: 1+ (1-5 groups), 2+ (6-10 groups), 3+ (11-20 groups), and 4+ (> 20 groups). Genomic DNA was extracted from residual materials of thyroid FNAs after cytologic diagnosis.<BR><B>RESULTS: </B>Approximately 49% of thyroid FNA samples had low cellularity (1-2+). DNA yield is proportionate with increased cellularity and increased nearly 4-fold from 1+ to 4+ cellularity in cytologic samples. When applied to BRAF mutational assay, using a cutoff of 6 groups of follicular cells with 10+ cells per group, 96.7% of cases yielded enough DNA for at least one testing for BRAF mutation. Five specimens (11.6%) with lower cellularity did not yield sufficient DNA for duplicate testing. Comparison of Sanger sequencing to allele-specific polymerase chain reaction methods shows the latter confers better sensitivity in detection of BRAF mutation, especially in limited cytologic specimens with a lower percentage of malignant cells.<BR><B>CONCLUSIONS: </B>This study demonstrates that by using 6 groups of 10+ follicular cells as a cutoff, nearly 97% of thyroid FNA samples contain enough DNA for BRAF mutational assay. Careful selection of a molecular testing system with high sensitivity facilitates the successful conduction of molecular testing in limited cytologic specimens. Cancer (Cancer Cytopathol) 2014;122:114-22 © 2013 American Cancer Society.