Sociodemographic and age-based markers for higher levels of health care access have been linked with higher incidence rates of papillary thyroid cancer in a recent study.

The incidence of papillary thyroid cancer is on the rise, possibly due to overdiagnosis of subclinical disease, suggested Luc G.T. Morris, MD, MSc, of Memorial Sloan-Kettering Cancer Center, New York, New York, and colleagues in their report in Thyroid (2013;23[7]:885-891). To determine whether overdiagnosis was indeed occurring, the investigators used Surveillance, Epidemiology, and End Results (SEER) data to examine US papillary thyroid cancer incidence trends in Medicare-age and non–Medicare-age cohorts over the course of 3 decades.

The data showed that papillary thyroid cancer incidence is rising most rapidly among Americans older than age 65 years who have broad health coverage through Medicare (annual percentage change: 8.8%). For persons younger than age 65 years, a group for which insurance coverage is not universal, the annual percentage change in papillary thyroid cancer incidence has been lower, at 6.4%.

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Incidence ranged widely across US counties, from zero to 29.7 per 100,000. County papillary thyroid cancer incidence was significantly correlated with all nine sociodemographic markers of health care access included in the study:

  • Incidence was positively correlated with rates of college education, white-collar employment, and family income.
  • Incidence was negatively correlated with percentage of residents who were uninsured, in poverty, unemployed, of nonwhite ethnicity, non–English-speaking, and lacking high-school education.

Mortality rates for papillary thyroid cancer did not change over the 30 years analyzed, despite the threefold increase in incidence over that time.

“Together with the large subclinical reservoir of occult papillary thyroid cancers, these data provide supportive evidence for the widespread overdiagnosis of this entity,” concluded Morris and team.