Incidence and Survival in Reproductive-Aged Women with Differentiated Thyroid Cancer: United States SEER 18 2000-2016.

Incidence of differentiated thyroid cancer has increased in the United States and globally with disproportionate increases observed among women. Recent data suggest that factors other than increased detection may underlie this increase. To understand incidence and survival patterns in differentiated thyroid cancer during a time period of increasing imaging, we examined data from a contemporary population-based sample of U.S. reproductive-aged women. Women aged 20-49 years ( = 61,552) diagnosed with papillary thyroid cancer (PTC) or follicular thyroid cancer (FTC) during 2000-2016 were identified from the U.S. National Cancer Institute Surveillance, Epidemiology, and End Results 18 registries database. For each age decade (20-29, 30-39, 40-49 years), we estimated age-adjusted average annual percentage changes in incidence using segmented and unsegmented regression models and 15-year survival. Results were stratified by race/ethnicity and cancer stage. The estimated incidence of PTC increased during 2000-2016 among women aged 20-29 years and during 2000-2012 among women aged 30-49 years. During 2012-2016, incidence stabilized among women aged 30-39 years and decreased among women aged 40-49 years. For FTC, incidence decreased slightly among women aged 20-29 years and was rather stable among those aged 30-49 years during 2000-2016, although increases were observed among non-Hispanic black women aged 30-49 years. By stage, the percentage increase in PTC incidence was largest for regional disease. Fifteen-year estimated survival was generally high but somewhat lower among women aged 40-49 years than those aged 20-39 years. Survival was similar for PTC and FTC except among women aged 20-29 years, for whom survival was modestly lower with FTC than PTC. Our findings confirm increasing incidence of PTC among U.S. women aged 20-29 years, a recent stabilization of PTC incidence in women 30-49 years, and stable to decreasing incidence of FTC. Increased detection based on imaging is unlikely to fully explain the continued increase in PTC incidence, given the increasing incidence of regional disease and routine imaging occurring less often among premenopausal than postmenopausal women. Although survival is generally high, treatment often requires surgery and lifelong medications. Further investigations into contributors to these trends are warranted to reduce future morbidity in reproductive-aged women.