Thyroid cancer incidence plateaued during 2010s after rising from 1975 to 2009
Key takeaways:
- The incidence rate of thyroid cancer remained close to its 2009 peak of 14.6 cases per 100,000 people throughout the 2010s.
- Thyroid cancer metastasis and mortality rates remained unchanged from 1975 to 2019.
After rising over a 35-year period, thyroid cancer incidence in the U.S. plateaued from 2010 to 2019, according to findings published in The Lancet Diabetes & Endocrinology.
In a retrospective analysis of data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) and National Center for Health Statistics databases, researchers found no changes in metastasis or mortality rates for adults diagnosed with thyroid cancer from 1975 to 2019, despite a rising incidence rate during that time. These findings reveal thyroid cancer may have been overdiagnosed in more recent years, according to Zachary Zumsteg, MD, associate professor of radiation oncology and biomedical sciences, and radiation oncology director of the head and neck oncology disease research group at Cedars-Sinai. However, Zumsteg noted the plateau of thyroid cancer incidence in the past 10 years of the study may be indicative of a change in diagnostic practices.
“There have been recommendations from the American Thyroid Association, the Choosing Wisely guidelines and the U.S. Preventive Services Task Force all saying do not screen asymptomatic patients for thyroid cancer,” Zumsteg told Healio. “What we found is there has been an improvement in that the rate of thyroid cancer is no longer increasing. However, it has simply plateaued at peak levels. It is good that thyroid cancer incidence is no longer increasing from overdiagnosis, but we haven’t been able to turn around and reduce the amount of overdiagnosis going on in the U.S.”
Researchers obtained data from 91,968 adults aged 25 to 85 years diagnosed with thyroid cancer in the U.S. from 1975 to 2019 (74.5% women). Incidence rates are age-adjusted using the U.S. Census Bureau standard population from 2000.
Incidence rate trends
Annual thyroid cancer incidence rate rose from five cases per 100,000 people in 1975 to 14.6 cases per 100,000 people in 2009. Incidence cases remained at a plateau for the remainder of the study, with a 2019 incidence rate of 14.1 cases per 100,000 people. The incidence rate for women rose from 6.6 cases per 100,000 people in 1975 to a peak of 22.2 cases per 100,000 people in 2014. Thyroid cancer incidence increased for men from 3.4 cases per 100,000 people in 1975 to a peak of 8.1 cases per 100,000 people in 2012.
The metastasis rate at diagnosis was 0.4 cases per 100,000 people in 1975 and 2019. Both women and men had a stable metastasis rate throughout the study.
Thyroid cancer mortality did not change during the study, remaining at 0.5 deaths per 100,000 people in 1975 and 2019. Women had a slight decline in thyroid cancer mortality from 0.6 deaths per 100,000 people in 1975 to 0.5 deaths per 100,000 people in 2019. For men, thyroid cancer mortality rates increased slightly from 0.4 cases per 100,000 people in 1975 to 0.5 cases per 100,000 people in 2019.
Zumsteg said greater use of thyroid ultrasounds and imaging in health care contributed to rising reported thyroid cancer incidence over time.
“As a medical profession, we’re doing more imaging on patients in general,” Zumsteg said in an interview. “The more imaging we do, the more that we find these nodules in the thyroid that are asymptomatic. It’s hard for physicians when they see something and they don’t know what it is to not look into it.”
Before 1995, thyroid cancer diagnoses were similar across all age groups for women and men. After 1995, middle-aged women tended to have larger incidence rate increases than younger and older age groups. For men, thyroid cancer incidence increased more for those aged 50 years and older in later years of the study compared with other age groups. Zumsteg said those age groups may have larger incidence rates because they may be more engaged with the health care system.
How to reduce incidence
Multiple initiatives are needed for thyroid cancer incidence to increase, according to Zumsteg. He said guidance on thyroid cancer screening and the need to avoid asymptomatic screening needs to be better communicated to health care professionals across all specialties.
Additionally, Zumsteg suggested better criteria are needed to determine which thyroid nodules should be biopsied or investigated further.
“There are multiple molecular tests that are now available where it can tell you how likely a nodule is to be a thyroid cancer,” Zumsteg told Healio. “We need more research and tests to not only say what is likely to be a thyroid cancer, but a life-threatening thyroid cancer.”
Zumsteg added greater acceptance of active surveillance for low-risk thyroid cancer is also needed.
“We can’t eliminate all overdiagnosis,” Zumsteg said. “But if we can at least eliminate or minimize overtreatment, then we can prevent some of the most serious harms that can come from overdiagnosis.”
For more information:
Zachary Zumsteg, MD, can be reached at zachary.zumsteg@cshs.org.
Collapse
Read more about