August 18, 2016
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Overdiagnosis accounts for increased thyroid cancer incidence

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The incidence of thyroid cancer worldwide has consistently been increasing in recent decades and may be attributable to the use of new diagnostic techniques coupled with increased medical surveillance and access to health care services, according to a perspective published in The New England Journal of Medicine.

Perspective from

However, no substantial change in thyroid cancer-related mortality has been observed despite rising incidence, according to Salvatore Vaccarella, PhD, of the International Agency for Research on Cancer in Lyon, France, and colleagues.

Vaccarella and colleagues calculated the number of overdiagnosed cases of thyroid cancer in 12 countries — Australia, Denmark, England, Finland, France, Italy, Japan, Norway, South Korea, Scotland, Sweden and the United States — using data from the International Agency for Research on Cancer’s reference publication Cancer Incidence in Five Continents.

“Countries such as the [United States], Italy and France have been most severely affected by overdiagnosis of thyroid cancer since the 1980s, after the introduction of ultrasonography, but the most recent and striking example is the Republic of Korea,” Vaccarella said in a press release. “A few years after ultrasonography of the thyroid gland started being widely offered in the framework of a population-based multi-cancer screening, thyroid cancer has become the most commonly diagnosed cancer in women in the Republic of Korea, with approximately 90% of cases in 2003 to 2007 estimated to be due to overdiagnosis.”

Researchers conclude that overdiagnosed cases in women from 2003 to 2007 account for 70% to 80% of cases in the United States, Italy, France and Australia and 50% of cases in Japan, the Nordic countries, England and Scotland. Overdiagnosis in men for the same period accounted for 70% of cases in France, Italy and South Korea, 45% in the United States and Australia and less than 25% in the other countries evaluated.

“More than half a million people are estimated to have been overdiagnosed with thyroid cancer in the 12 countries studied,” Christopher P. Wild, PhD, director of the International Agency for Research on Cancer, said in the release. “The drastic increase in overdiagnosis and overtreatment of thyroid cancer is already a serious public health concern in many high-income countries, with worrying signs of the same trend in low- and middle-income countries. It is, therefore, critical to have more research evidence in order to evaluate the best approach to address the epidemic of thyroid cancer and to avoid unnecessary harm to patients.” – by Amber Cox

Disclosure: The researchers report no relevant financial disclosures.

Thyroid cancer overdiagnosis Infographic