The Study
Association between screening and the thyroid cancer “epidemic” in South Korea: evidence from a nationwide study
This study found that more people in South Korea were getting thyroid cancer diagnoses around the same time that more people started getting ultrasound scans — but it didn’t prove the scans caused the extra diagnoses. It just shows they happened together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Doctors started using ultrasounds to check everyone’s thyroid, even if they felt fine, and found tons of tiny lumps that would never hurt anyone.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1No, it’s not more people dying — it’s just more people being told they have cancer that doesn’t need treatment.
- 2Thyroid cancer diagnoses jumped 6.4x in 9 years; 94% of new cases were tiny tumors (<20 mm); death rates stayed the same.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The BMJ
Year
2016
Authors
Sohee Park, C. Oh, Hyunsoon Cho, J. Lee, K. Jung, J. Jun, Y. Won, H. Kong, K. Choi, You Jin Lee, Jin-Soo Lee
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Claims (6)
Getting everyone screened for thyroid cancer finds a lot of harmless lumps that would never hurt you, so more people are told they have cancer—but it doesn’t save any lives.
In South Korea, more people were diagnosed with thyroid cancer between 1999 and 2012, but the number of people dying from it didn’t go up — which suggests doctors are just finding harmless lumps that wouldn’t have hurt anyone, not more dangerous cancers.
In South Korea, between 1999 and 2008, doctors started finding a lot more tiny thyroid cancers—so many that the overall number jumped more than six times. But almost all of these were very small tumors that probably wouldn’t have caused any harm if left alone.
More people were diagnosed with thyroid cancer between 1999 and 2008, and most of that increase came from ultrasounds finding tiny, harmless lumps in the thyroid—so it’s not that more people got sick, but that we’re just finding tiny things we wouldn’t have noticed before.
In South Korea, more and more people started finding thyroid cancer through routine scans between 1999 and 2008 — and this happened right after doctors began using ultrasound machines much more often thanks to new health rules.
More thyroid cancers were found between 1999 and 2008, but almost all of them were tiny lumps that doctors couldn’t even feel during a regular checkup — so they probably found them by accident while doing scans or tests for other reasons.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.