The assessment of thyroid nodules is a common clinical challenge. Fine-needle aspiration (FNA) is the standard preoperative tool for thyroid nodule diagnosis. However, up to 30% of the samples are classified as indeterminate. This often leads to unnecessary surgeries. In this study, we evaluated the added value of next-generation sequencing (NGS) for helping in the diagnosis of FNA samples.
Methods and Results
We retrospectively analysed 34 indeterminate FNA samples for which surgical resection was performed. DNA was obtained from cell blocks or from stained smears and subjected to NGS to analyse mutations in 50 genes. Mutations in BRAF, NRAS, KRAS and PTEN that are known to be involved in thyroid cancer biology were detected in 7 FNA samples. The presence of a mutation in these genes was a strong indicator of cancer because 5 (71%) of the mutation-positive FNA samples had malignant diagnosis after surgery. Moreover, the cancer risk in nodules with indeterminate cytological diagnosis but with a negative molecular test was of only 8%.
This study demonstrates that thyroid FNA can be successfully analysed by NGS. The detection of mutations known to be involved in thyroid cancer improves the sensitivity of thyroid FNA diagnosis.