---
title: Thyroid cancer in South Korea: what the evidence says about the epidemic, the correction, and what it cost
publication: Medical Insights Korea
section: news
category: Thyroid
canonical_url: https://medicalinsightskorea.com/news/thyroid-cancer-in-south-korea
author: Chloe Moon
published: 2026-09-02T11:05:00+09:00
modified: 2026-09-02T11:05:00+09:00
content_type: reporting
license: Quotation permitted with attribution to Medical Insights Korea and a link to the canonical URL.
---

# Thyroid cancer in South Korea: what the evidence says about the epidemic, the correction, and what it cost

Korea found more thyroid cancer than any country in history and almost none of the extra deaths that would justify it. This is what the published evidence establishes, and where it stops.

## Answer

South Korea's standardised thyroid cancer incidence rose from 7.41 per 100,000 in 1999 to 75.06 in 2012 before falling to 42.50 in 2015 and rising again to 60.13 by 2021, while annual deaths remained between 330 and 394 throughout 2005 to 2018 and the age-standardised mortality rate fell from 1.28 to 0.80 per 100,000.

## Key takeaways

- Korea's standardised thyroid cancer incidence went from 7.41 per 100,000 in 1999 to a peak of 75.06 in 2012, fell to 42.50 by 2015, and rose again to 60.13 by 2021.
- Annual thyroid cancer deaths in Korea stayed between 330 and 394 across 2005 to 2018 while annual new diagnoses ranged from 12,833 to 44,798.
- 94.4 percent of the 1999–2008 increase consisted of tumours smaller than 20 mm found mainly by screening, and an international analysis attributed more than 85 percent of Korean female cases in 2013–17 to overdiagnosis.
- Higher income was associated with more screening, more diagnoses and more postoperative complications; lower income with higher mortality — the reverse of the pattern the same study found for lung cancer and stroke.
- Of 8,969 Korean patients with papillary thyroid microcarcinoma, 2 died of it, and the Korean Thyroid Association's 2025 guideline now permits watching such tumours rather than removing them.

## Full article

Between 1999 and 2012 South Korea multiplied its thyroid cancer diagnoses tenfold. It is the largest documented cancer detection epidemic anywhere, it has been taught for a decade as the definitive case of overdiagnosis, and the country is now further into the aftermath than any other.

This article collects what the published evidence establishes, links to our reporting on each part, and is explicit about where the questions a patient actually has run past what anyone has measured.

### The curve, and the curve that did not follow it

**Standardised thyroid cancer incidence per 100,000, South Korea**

| Year | Rate |
| --- | --- |
| 1999 | 7.41 |
| 2012 (peak) | 75.06 |
| 2015 | 42.50 |
| 2021 | 60.13 |

Deaths did not move with any of it. Across 2005 to 2018 the annual count of thyroid cancer deaths stayed between 330 and 394 while annual diagnoses ranged from 12,833 to 44,798, and the age-standardised mortality rate fell from 1.28 to 0.80 per 100,000.

**330 to 394** — annual thyroid cancer deaths in Korea across 2005 to 2018, while annual diagnoses ranged from 12,833 to 44,798  
_Source: Jung KW et al., International Journal of Surgery, 2025_

That divergence is the whole argument. A nationwide review of how the tumours were found showed 94.4 percent of the 1999–2008 increase was tumours under 20 mm detected mainly by screening, and 97.1 percent of the total increase was localised or regional disease — the signature of looking rather than of illness.

**Reported in full**

- [Korea's thyroid cancer epidemic was supposed to be over. The incidence curve turned back up in 2015](https://medicalinsightskorea.com/news/korea-thyroid-cancer-incidence-rising-again)
- [Did thyroid cancer screening in South Korea save lives?](https://medicalinsightskorea.com/faq/thyroid-cancer-screening-korea-does-it-save-lives)

### Who was screened, and who died

Korea never had a national thyroid screening programme. The scans were opportunistic, and the strongest single predictor identified in a national survey of women was having attended for a breast ultrasound — 2.71 times the odds of thyroid screening against no breast screening, where mammography alone raised them only 1.47-fold.

The result was distributed by income. Higher income went with more screening, more diagnoses and more postoperative complications; lower income went with higher mortality. For lung cancer and stroke, analysed as controls by the same team, higher income predicted lower incidence and lower mortality — the ordinary direction. And when Korea began to correct course, incidence and complications fell fastest among the higher-income group that had been over-examined first.

**Reported in full**

- [Korea's thyroid cancer epidemic followed income upward. So did the correction, and the deaths did not](https://medicalinsightskorea.com/news/thyroid-overdiagnosis-korea-income-gradient)

### What the operation costs

Overdiagnosis matters only because treatment does something to people. Pooled across 199 studies and 304,352 patients, transient recurrent laryngeal nerve injury ran from 2 percent after near-total thyroidectomy to 10 percent after completion thyroidectomy, with permanent injury worst after reoperation. Highest risk of hypoparathyroidism belongs to the combination that follows a cancer diagnosis: total thyroidectomy with lateral neck dissection.

Those pooled figures are also a lesson in measurement. A Korean series of 1,000 consecutive transaxillary robotic operations that examined every patient's vocal cords found transient nerve injury in 4.1 percent — roughly four times what pooled international data assigns to that approach, because a transient palsy is counted only where somebody looks for it.

**Reported in full**

- [Pooled data on 304,352 thyroid operations puts nerve injury between 1 and 10 percent. The lowest figure belongs to the approach with the most selected patients](https://medicalinsightskorea.com/news/thyroidectomy-complication-rates-what-surgery-costs)
- [A thousand consecutive Korean robotic thyroidectomies report four times the nerve injury that pooled data gives the approach. The difference is who looked](https://medicalinsightskorea.com/news/transaxillary-robotic-thyroidectomy-korea-1000-cases)

### The alternative to operating

Of 8,969 Korean patients with papillary thyroid microcarcinoma treated between 1994 and 2017, 107 died and two died of the thyroid cancer. In June 2025 the Korean Thyroid Association published the country's first guideline permitting active surveillance for such tumours: ultrasound and thyroid function every six months for two years then annually, with surgery if the tumour progresses.

In a Korean cohort of 927 patients, what predicted choosing surveillance over immediate lobectomy included prior awareness that it existed and higher income. Pooled data records progression in 14.53 percent and no thyroid cancer deaths in either the surveillance or the immediate surgery arm — alongside higher complication and recurrence rates among those who did come to surgery later.

**Reported in full**

- [Korea now has a guideline for not operating on thyroid cancer. Who takes it up is partly a question of income](https://medicalinsightskorea.com/news/thyroid-active-surveillance-korea-who-chooses-it)
- [Can a small thyroid cancer be watched instead of removed?](https://medicalinsightskorea.com/faq/small-thyroid-cancer-watch-instead-of-surgery)

### How the numbers get misreported

In 2024 a study of 434,228 Korean patients reported thyroid cancer-specific mortality rising from 0.76 to 2.70 per 1,000 person-years among those diagnosed between 2013 and 2018 — deaths climbing while diagnoses fell. The Korea Central Cancer Registry replied in the same journal that the figure counts deaths among diagnosed patients and is therefore a case fatality rate, not mortality, and that population mortality fell over the same span.

> **Both numbers were correct**  
> Neither side disputed the arithmetic. A statistic that is accurately calculated and misnamed travels further than one that is wrong, because nothing about it fails a check — which is why the distinction between mortality and case fatality is worth more attention than it usually gets.

**Reported in full**

- [Korea's cancer registry told a journal that a study of rising thyroid cancer deaths had not measured mortality](https://medicalinsightskorea.com/news/thyroid-mortality-versus-case-fatality-korea)

### Where the evidence runs out

1. Nobody knows what is driving the renewed rise in incidence since 2015. It appears in distant-stage disease as well as localised, which is not what overdetection produces, and the authors who documented it decline to explain it.
2. Registry data records diagnoses, not disease, and cannot separate more cancer from more looking. Stage at diagnosis is itself partly a function of imaging intensity.
3. Nothing in this evidence explains why lower-income Koreans die of thyroid cancer more often. Later presentation, comorbidity and treatment access are all candidates and none has been tested.
4. No randomised comparison exists between active surveillance and immediate surgery, or between remote-access and conventional thyroidectomy. Every comparison cited here is between patients who chose or were chosen.
5. The complication meta-analyses are not Korean, and the Korean surgical figures come from single high-volume institutions rather than from national data.

> **How this page is maintained**  
> This is the overview for our thyroid reporting and is updated as pieces are added or as the underlying evidence changes; the modification date at the top reflects the last such change. Every figure on it is drawn from a source listed below and reported in full in the linked article.

## Sources

- Yoon YJ, Seo JM, Kim JS, Choi YM, Kim WG. Long-Term Trends in Thyroid Cancer Incidence and Mortality in Korea: Analysis of Korean National Data. Endocrinology and Metabolism 2026. doi:10.3803/enm.2025.2807. PMID:42324644. https://doi.org/10.3803/enm.2025.2807
- Park S, Oh CM, Cho H, Lee JY, Jung KW, Jun JK, et al. Association between screening and the thyroid cancer "epidemic" in South Korea: evidence from a nationwide study. BMJ 2016;355:i5745. doi:10.1136/bmj.i5745. PMID:27903497. https://doi.org/10.1136/bmj.i5745
- Jung KW, Park EH, Kang MJ. Clarifying the misinterpretation of case-fatality rate as mortality in thyroid cancer studies. International Journal of Surgery 2025;111(6):4103-4104. doi:10.1097/js9.0000000000002133. PMID:40085754. https://doi.org/10.1097/js9.0000000000002133
- Kang HY, Kim I, Kim YY, Bahk J, Khang YH. Income differences in screening, incidence, postoperative complications, and mortality of thyroid cancer in South Korea: a national population-based time trend study. BMC Cancer 2020;20(1):1096. doi:10.1186/s12885-020-07597-4. PMID:33176753. https://doi.org/10.1186/s12885-020-07597-4
- Lee E, Jeong SH, Nam CM, Jun JK, Park EC. Role of breast cancer screening in the overdiagnosis of thyroid cancer: results from a cross-sectional nationwide survey. BMC Women's Health 2023;23(1):64. doi:10.1186/s12905-023-02205-6. PMID:36782225. https://doi.org/10.1186/s12905-023-02205-6
- Lee EK, Kim MJ, Kang SH, Koo BS, Kim K, Kim M, et al. 2025 Korean Thyroid Association Clinical Management Guideline on Active Surveillance for Low-Risk Papillary Thyroid Carcinoma. Endocrinology and Metabolism 2025;40(3):307-341. doi:10.3803/enm.2025.2461. PMID:40598902. https://doi.org/10.3803/enm.2025.2461
- Heo J, Ryu HJ, Park H, Kim TH, Kim SW, Oh YL, Chung JH. Mortality rate and causes of death in papillary thyroid microcarcinoma. Endocrine 2024;83(3):671-680. doi:10.1007/s12020-023-03510-8. PMID:37814113. https://doi.org/10.1007/s12020-023-03510-8
- Awawda R, Merchavy S, Elhadi UA, Safia A. Prevalence and determinants of recurrent laryngeal nerve injury after thyroidectomy: a Systematic Review and meta-analysis. Frontiers in Endocrinology 2026;17:1764332. doi:10.3389/fendo.2026.1764332. PMID:42137353. https://doi.org/10.3389/fendo.2026.1764332
- Park J, An S, Bae JS, Kim K. Perioperative and oncologic outcomes of 1,000 consecutive single-port transaxillary robotic thyroidectomy (SP-TART). Surgical Endoscopy 2026. doi:10.1007/s00464-026-13193-7. PMID:42527738. https://doi.org/10.1007/s00464-026-13193-7
- Li M, Dal Maso L, Pizzato M, Vaccarella S. Evolving epidemiological patterns of thyroid cancer and estimates of overdiagnosis in 2013-17 in 63 countries worldwide: a population-based study. The Lancet Diabetes & Endocrinology 2024;12(11):824-836. doi:10.1016/s2213-8587(24)00223-7. PMID:39389067. https://doi.org/10.1016/s2213-8587(24)00223-7

## Citation

Chloe Moon (2026). "Thyroid cancer in South Korea: what the evidence says about the epidemic, the correction, and what it cost". Medical Insights Korea. https://medicalinsightskorea.com/news/thyroid-cancer-in-south-korea

Retrieved from https://medicalinsightskorea.com/news/thyroid-cancer-in-south-korea