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Who Is Most Likely to Have Thyroid Cancer?

Study suggests insurance-covered treatment may contribute to thyroid cancer over diagnosis

Thyroid cancer is the third fastest rising cancer diagnosis in the United States. The number of thyroid cancer diagnoses has more than tripled in the last 30 years, but the number of people who have died from the disease remains the same. Is this "thyroid cancer epidemic" due to an increase in the disease or because insurance-covered screening detects small tumors that may never cause symptoms or harm?

Focus article photo

Thyroid cancer is over diagnosed says Louise Davies, MD, pictured here at Norris Cotton Cancer Center.

The rapid increase in papillary thyroid cancer in the US may not be linked to an increase in occurrence, but to an increase in the diagnosis of pre-cancerous conditions and to a person's insurance status.

That is the conclusion of a paper recently published in Thyroid, a peer reviewed journal of the American Thyroid Association, which included the research of senior author Louise Davies, MD, MS, a head and neck surgeon at Dartmouth-Hitchcock Norris Cotton Cancer Center and researcher with The Veteran's Administration Outcomes Group, Geisel School of Medicine at Dartmouth, and The Dartmouth Institute.

In addition researchers found that higher education levels and higher rates of white collar employment were also associated with increased diagnosis rates.

More insured patients diagnosed with thyroid cancer

"This work shows that access to health care is an important driver in the rising incidence of thyroid cancer," said Davies. "People with insurance are more likely to be diagnosed with thyroid cancer than those without insurance." Papillary thyroid cancer is rising 8.8 percent in Americans over age 65 who have Medicare. Among adults under age 65, who do not have access to Medicare, the rate of increase is 6.4 percent. The mortality rate from thyroid cancer, however, has not changed.

"We did the study to understand who is at risk of being diagnosed with thyroid cancer, which is now— like prostate cancer—recognized to be a disease that is commonly over diagnosed," said Davies.

Over diagnosis of thyroid cancer can lead to unnecessary treatment

Over diagnosis is the identification of a cancer that would otherwise not have been identified in a person's lifetime.

"The findings are counterintuitive for many: having good health insurance puts you at risk for something bad—the unnecessary identification and treatment of a cancer that was never destined to cause a problem," said Davies.

Davies and lead author Luc Morris, MD, MSc, Memorial Sloan-Kettering Cancer Center, used Surveillance, Epidemiology and End Results (SEER) data to examine papillary thyroid cancer incidence trends in Medicare age and non-Medicare age adults over three decades. They looked at 497 counties in the US over three decades. The Geospatial Shared Resource at Norris Cotton Cancer Center helped the team analyze and map the information.

How will this finding change the practice of medicine? According to Davies, "As a next step we should look to protect patients from unnecessary workups of thyroid findings that do not present a significant threat to their health."

August 19, 2013