Incidence and predictive factors of inadequate fine-needle aspirates for BRAF(V600E) mutation analysis in thyroid nodules.
OBJECTIVE
BRAF(V600E) mutation (valine-to-glutamate substitution at residue 600 of the B-type Raf kinase gene) analysis from thyroid aspirates is increasingly used as a prognostic or diagnostic marker. However, it is limited under some conditions. The purpose of this study was to assess the incidence and predictive factors of thyroid nodules with specimens inadequate for BRAF(V600E) mutation analysis.


METHODS
We performed a retrospective cohort study of consecutive patients who underwent ultrasound-guided fine-needle aspiration (FNA) and molecular testing of aspiration specimens. Patients who had inadequate specimens in both allele-specific polymerase chain reaction and direct DNA-sequencing methods were selected. Univariate and multivariate logistic regression analyses were performed to identify predictive factors of specimens inadequate for molecular tests.


RESULTS
Specimens inadequate for BRAF(V600E) mutation analysis were seen in 168 of 7001 (2.4%) patients. Factors, including patient age and sex, nodule size, ultrasound diagnosis, the presence of calcification, and cystic changes within thyroid nodules, were not significant predictors of inadequate mutation analysis. Oval-to-round or irregular shapes (e.g., not taller-than-wide) and final benign results were significant factors in univariate analysis (p = 0.0002 and p = 0.0013, respectively). However, nodules aspirated by operators with less than 1 year of experience (odds ratio [OR], 3.005; p = 0.0070), and those that had spiculated margins (OR, 6.139; p = 0.0142), isoechogenicity (OR, 10.374; p = 0.0442), or nondiagnostic cytologic findings (OR, 73.637; p = 0.0055) remained significant risk factors after adjustment in multivariable analysis.


CONCLUSIONS
Thyroid nodule specimens inadequate for BRAF(V600E) mutation analysis were frequently associated with FNA aspiration performed by inexperienced operators, nondiagnostic cytologic findings, benign nodules on final diagnosis, and probably benign ultrasound findings, such as isoechogenicity and not-taller-than-wide shape.
1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Korea.
Kwang Hwi
KH
Lee
Hyun Su
HS
Kim
Boo-Kyung
BK
Han
Eun Young
EY
Ko
Chang-Seok
CS
Ki
Jung Hee
JH
Shin
D000328:Adult; D000368:Aged; D000483:Alleles; D014408:Biomarkers, Tumor; D044963:Biopsy, Fine-Needle; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000601:surgery; D016606:Thyroid Nodule / Q000235:genetics* / Q000601:surgery; D018084:Ultrasonography, Interventional
D014408:Biomarkers, Tumor; D048493:Proto-Oncogene Proteins B-raf