Most Cases of Papillary Thyroid Cancer May Be Overdiagnosed, Study Finds

The growing use of thyroid ultrasound may lead to small and relatively harmless cancers being diagnosed at higher rates.

Matt MacKenzie

Sept. 8, 2026

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Key Highlights

Most papillary thyroid cancers diagnosed over the past three decades are likely overdiagnosed, with minimal impact on mortality rates.
Increased use of ultrasound has significantly contributed to the rise in detected cases, many of which are slow-growing and harmless.
Overdiagnosis disproportionately affects women, with hundreds of thousands potentially receiving unnecessary treatment.
Reducing thyroid ultrasound usage by one-third could lower diagnoses by 17%, decreasing overtreatment without increasing death risk.
More selective screening strategies are recommended to balance early detection with avoiding unnecessary interventions.

Over the past three decades, most cases of papillary thyroid cancer may have been overdiagnosed, according to a new study.

Overdiagnosis in this case means that incidences of the cancer were detected and treated surgically without improving population rates of death. Other researchers have shown that approximately 10% of adults have small papillary thryoid cancer nodules at end of life that did not contribute to their death.

The research team looked at data from 1991 through 2019 and estimated that 72-94% of papillary thyroid cancers were likely overdiagnosed during that time. That increase is largely tied to the growing use of ultrasound, which can detect small and slow-growing cancers that are unlikely to cause harm.

Overdiagnosis affected women more than men; between 443,000 and 574,000 women and 108,000 to 155,000 men were overdiagnosed over those 28 years. The researchers found that a one-third reduction of thyroid ultrasound would reduce diagnoses by 17%. This suggests more selective use of thyroid ultrasound could significantly reduce unnecessary diagnoses and treatments without increasing the risk of death.