# Thyroid nodule FNA, Bethesda cytology & molecular classifiers

Source: https://onco.cc/technologies/thyroid-fna-molecular/  
OnCo record `thyroid-fna-molecular` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Thyroid fine-needle aspiration takes a needle sample from a thyroid lump and grades it on a six-level scale; when the result is uncertain, a gene test on the same sample can often rule cancer out and avoid surgery.

## Summary

Ultrasound-guided fine-needle aspiration reported by the Bethesda System (I-VI). Indeterminate categories (III-IV, ~20% of nodules) historically went to diagnostic lobectomy; molecular classifiers such as Afirma GSC (RNA expression, Veracyte) and ThyroSeq v3 (DNA/RNA NGS) have negative predictive values around 95-97%, halving unnecessary surgery. TI-RADS ultrasound scoring decides which nodules to biopsy at all.

## Fields

- Kind: Technology
- Status: standard-of-care
- Last checked: 2026-09-07
- Principle: Cytology is combined with gene-expression or mutation/fusion panels calibrated on surgical outcomes.
- Strengths: Avoids surgery for most benign indeterminate nodules; Detects BRAF, RET, RAS, TERT for risk and therapy planning
- Limitations: Cost; positive predictive value is moderate; Overdiagnosis of indolent microcarcinoma remains the systemic problem

## Sources

- Ali et al., The 2023 Bethesda System for Reporting Thyroid Cytopathology (Thyroid 2023): https://doi.org/10.1089/thy.2023.0141
- Haugen et al., 2015 American Thyroid Association management guidelines for thyroid nodules and differentiated thyroid cancer (Thyroid 2016): https://doi.org/10.1089/thy.2015.0020

## Connected records

- cancers: [Thyroid cancer](https://onco.cc/cancers/thyroid/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/)
- technologies: [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/), [RNA sequencing & expression profiling](https://onco.cc/technologies/rna-seq/), [Thyroglobulin, calcitonin and CEA in thyroid cancer follow-up](https://onco.cc/technologies/thyroid-cancer-markers/), [Ultrasound](https://onco.cc/technologies/ultrasound/)
- companies: [Veracyte (Decipher)](https://onco.cc/companies/veracyte/)
- terms: [Bethesda category (thyroid cytology)](https://onco.cc/terms/bethesda-category/), [TERT promoter mutation](https://onco.cc/terms/tert-promoter/)
- key papers: [The 2023 Bethesda System for Reporting Thyroid Cytopathology](https://onco.cc/key-papers/paper-ali-thyroid/)
- ideas: [Ultrasound restraint and surveillance to reverse thyroid cancer overdiagnosis](https://onco.cc/ideas/idea-thyroid-overdiagnosis-reversal/)
- bottlenecks: [Overdiagnosis and false alarms](https://onco.cc/bottlenecks/b-overdiagnosis/)
- drugs: [Afirma Genomic Sequencing Classifier](https://onco.cc/drugs/afirma/)

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