Incidence of Papillary Thyroid Cancer: Comparison of the Military and the General Population by Race and Tumor Stage/size

Background: A previous study found higher papillary thyroid cancer incidence in the US military than the general population with larger differences among Black than White individuals. This study compared the two populations in the incidence by sex, race, tumor stage, and size to assess possible factors related to identified differences.

Methods: Subjects were aged 18-59 in the military and general populations. Papillary thyroid cancer patients diagnosed during 1990-2013 were identified from the Department of Defense's Automated Central Tumor Registry (ACTUR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. Age-adjusted rates and incidence rate ratios (IRR) comparing ACTUR to SEER were calculated.

Results: Higher incidence rates in ACTUR than SEER were more obvious for Black (IRR=2.07, 95%CI=1.56-2.70) than White men (IRR=1.17, 95%CI=1.07-1.26) and for Black (IRR=2.30, 95%CI=1.91-2.71) than White women (IRR=1.50, 95%CI=1.38-1.64). Population differences by race were observed for localized tumors among both men and women and were larger for Black individuals. Differences were observed regardless of tumor size among Black men and White women, and in smaller tumors among Black women.

Conclusion: Higher incidence in the military than general population primarily in localized tumors suggests universal healthcare in the military may lead to earlier detection. The differences were larger among Blacks than Whites, suggesting universal access in the military may be more impactful among Black persons, who are less likely to have timely care than White persons in the general population. Nevertheless, observed differences for tumors > 2 cm suggest other factors may also play a role.