# Stop biopsying small thyroid nodules and never screen the thyroid

Source: https://onco.cc/ideas/idea-prev-thyroid-no-screening-no-small-biopsy/  
OnCo record `idea-prev-thyroid-no-screening-no-small-biopsy` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

South Korea's thyroid cancer rate rose 15-fold after ultrasound screening, with no fall in deaths. A firm rule not to biopsy nodules under 1 cm, and not to screen, would prevent this harm elsewhere.

## Summary

Korean thyroid overdiagnosis is the clearest natural experiment in the field, and incidence fell after the 2014 public debate without any mortality change. Guidelines already discourage biopsy of sub-centimetre nodules but practice varies. Propose national policy: no ultrasound thyroid screening, mandatory adherence to size thresholds, and public reporting of the thyroid cancer incidence-to-mortality ratio as a harm indicator.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Policy adoption reduces thyroid cancer incidence by at least 30% within five years with no change in thyroid cancer mortality.
- Rationale: Korea showed reversibility: incidence fell rapidly once biopsy thresholds were enforced.
- Proposed test: Interrupted time-series in adopting regions versus controls.
- Maturity: being-tested-at-scale
- Actor: policy

## Sources

- Bottleneck evidence (Overdiagnosis and false alarms): Welch & Black, Overdiagnosis in cancer (JNCI 2010): https://doi.org/10.1093/jnci/djq099

## Connected records

- cancers: [Thyroid cancer](https://onco.cc/cancers/thyroid/)
- fronts: [Early Detection & Screening](https://onco.cc/fronts/early-detection/)
- technologies: [Ultrasound](https://onco.cc/technologies/ultrasound/)
- bottlenecks: [Overdiagnosis and false alarms](https://onco.cc/bottlenecks/b-overdiagnosis/)
- key papers: [Overdiagnosis in cancer](https://onco.cc/key-papers/paper-welch-j-natl-cancer-inst/)

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