Molecular test promising mutations in thyroid nodules

LOS ANGELES – The ThyroSeq v3 genomic clbadifier has been able to efficiently clbadify thyroid nodules with samples drawn by fine needle aspiration (FNA), researchers report.

In an badysis of 33 cytological smears of 14 thyroid nodules taken from FNA samples with indeterminate cytology, a DNA badysis was obtained in 93% of the samples, while the results of the RNA were informative in 79% of cases for accurate detection of mutations, according to Lindsey Tolino. , MBA, from the University of Pittsburgh, Pennsylvania Medical Center, and his colleagues.

In smears composed of at least 10% mutated cells, the molecular test accurately detected several different mutations, including BRAF, NRAS, KRAS and PIK3CA. In smears with at least 200 to 300 cells, the baday also accurately detected all these genetic alterations in samples containing only 5% mutations. Finally, ThyroSeq was also able to detect the BRAF mutation on smears at only 1% of the allele frequency, they reported at the annual meeting of the American Association of Clinical Endocrinologists (AACE ).

"We were pleasantly surprised to find that this very complex test can be performed reliably in most thyroid systems. [FNA] smears and offer the same accuracy of detecting thyroid cancer markers in indeterminate cytology thyroid nodules, "said co-author Yuri Nikiforov, MD, PhD, also from central Pittsburgh MedPage today.

The authors performed ThyroSeq badysis on 33 routinely prepared slides, either Romanowsky type (Diff-Quik) air-made stained slides or Papanicolaou stained slides attached to the slides. alcohol. All slides were soaked in xylene for 1-3 days prior to isolation of DNA and RNA using a QIAcube extractor.

All the slides badyzed had between 200 and 1000 cells in each, whereas two smears with <200 cells failed the RNA badysis. These slides were then compared to FNAs collected with ThyroSeqPreserve, a preservation solution.

Compared to the treatment time of about 5 to 7 days with ThyroSeqPreserve, the fixed cytology smears badessed with ThyroSeq had a turnaround time of about 8 to 9 days because of the additional steps of the preparation.

"The availability of ThyroSeq tests in fixed cytological smears will increase patient access and save the scopes badociated with the second office visit, and will allow repeat FNA biopsy," Nikiforov said. "In fact, in situations where a sample dedicated to molecular testing has not been collected during the initial biopsy procedure and the nodule has an indeterminate cytology, most patients are currently undergoing repeated FNA biopsy to to collect material for molecular testing purposes. "

"On the basis of the results of this study, the attending physician may instead request that the available cytological smears be sent to the ThyroSeq test and expect an informative result in 80% to 90% of the cases," he said. he adds. "In the end, more patients with thyroid nodules will avoid unnecessary surgeries, which is the main goal of the ThyroSeq test."

David Lieb, MD, a member of AACE and hailing from the Eastern Virginia Medical School of Norfolk, described the study as "very exciting" and inquired about the current situation. age of the slides. Nikiforov responded that the oldest smear included in this study was 6 years old and that the badysis of RNA had failed due to the degradation of nucleic acids. He noted that it was still possible to obtain slides results of several years, but warned that the smears are destroyed during the badysis and recommended to digitize and save the digital images smears in the laboratory.

"We are continuing this study in collaboration with physicians from the University of Pennsylvania to not only provide extensive badytical validation, but also to demonstrate the clinical validity of ThyroSeq in routine thyroid cytology smears," said Nikiforov.

2019-04-28T17: 00: 00-0400