Updated detection guidelines drive decrease in US thyroid cancer incidence
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An analysis of U.S. registry data suggests that rates of thyroid cancer have plateaued in recent years after decades on the rise, with researchers pointing to stricter guidelines limiting the indications for fine-needle aspiration for thyroid nodules as a reason for the trend, according to findings published in JAMA.
“The incidence of thyroid cancer has increased dramatically over the past 3 decades, and there is controversy whether this increased incidence is due to increased detection of an existing reservoir of disease vs. a true increase in the occurrence of the disease, due to an environmental carcinogen or other factors,” Jennifer L. Marti, MD, assistant professor of surgery, breast and endocrine surgery at Weill Cornell Medicine in New York, told Healio. “With Surveillance, Epidemiology and End Results data, we observed a plateau and recent decline in the incidence of small papillary thyroid cancers. This is likely due to implementation of the 2009 American Thyroid Association guidelines limiting the indications for fine-needle aspiration (FNA) of subcentimeter thyroid nodules and stricter guidelines in 2015 advocating for no FNA of any subcentimeter thyroid nodules, even if suspicious. These findings demonstrate that thyroid cancer incidence rates are very sensitive to our use of medical technology to identify subclinical disease, and that the prior dramatic increase in incidence rates is more likely to have been due to increased detection, rather than a true increase in occurrence due to the environment or other causes such as obesity.”
In an observational study, Marti and colleagues analyzed trends in the age-adjusted incidence of thyroid cancer from 1992 to 2016 data from the Surveillance, Epidemiology and End Results (SEER) registry, a population-based cancer surveillance registry from 13 geographic regions representing 14% of the U.S. population. Researchers used segmented log-linear regression analysis to determine break points and annual percentage change in thyroid cancer incidence.
Between 1992 and 2009, age-adjusted thyroid cancer incidence in the U.S. increased from 5.7 per 100,000 to 13.8 per 100,000, with the greatest annual percentage change (6.6%; 95% CI, 6.2-7) occurring between 1998 and 2009.
The rate of increase slowed from 2009 to 2014, with thyroid cancer incidence rising from 13.8 per 100,000 to 14.7 per 100,000, or an annual percentage change of 2% (95% CI, 0.3-3.7).
Since 2014, the incidence of thyroid cancer has remained stable, Marti said, with an annual percentage change of 2.4% (95% CI, 7.5 to 3.1).
From 1992 until 2009, the incidence of subcentimeter thyroid cancers steadily increased 1.2 per 100,000 to 4.7 per 100,000, with the greatest annual percentage change of 9.1% (95% CI, 8.4-9.8) occurring between 1996 and 2009. The trend stabilized from 2009 to 2013 and then declined from 2013 to 2016.
“These findings indicate that overdiagnosis — diagnosis of a condition that would not cause a symptom or death — can be partially combated by decreased biopsies, and therefore spare thousands of patients the potential harms of unnecessary treatments, such as thyroidectomy and radioactive iodine, as well as associated anxiety, and personal financial burdens that may ensue,” Marti said. “We should consider overdiagnosis occurring across the board in all areas of medicine, especially in cancer screening programs.”
Marti said researchers should continue to examine the thyroid cancer incidence trends as the ATA guidelines for thyroid FNA are more widely adopted, and consider how to limit indications for biopsies and subsequent overdiagnosis for other indolent cancers. – by Regina Schaffer
For more information:
Jennifer L. Marti, MD, can be reached at the Department of Surgery at Weill Cornell Medicine, 420 E. 70th St., New York, NY 10065.
Disclosures: One of the study authors reports he has received personal fees from Rakuten Aspyrian and that his lab has received research funding from AstraZeneca and Illumina.
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