Incidence and Survival of Differentiated Thyroid Cancer in Pre-menopausal Women: United States SEER 2000-2015

  • Introduction: Incidence of differentiated thyroid cancer (TC), particularly papillary TC (PTC), has increased in the United States (US) since the 1970s. Disproportionate increases observed among women have led to interest in hormonal exposures as possible causes of this trend.
     
    Methods: Women diagnosed at ages 20-29 (N=10,875), 30-39 (N=20,960), and 40-49 (N=25,247) with PTC and follicular TC (FTC) from 2000-2015 were identified from the US SEER18 Registries Database. Annual percentage changes (APC)s and corresponding 95% confidence intervals (CI)s in incidence and ten-year overall survival were estimated by tumor histology and race/ethnicity (Non-Hispanic [NH]-white, NH-black, NH-Asian/Pacific Islander, Hispanic) for each age decade.
     
    Results: TC incidence (APC, 95% CI) increased for women ages 20-29 (3.40, 2.93-3.87), 30-39 (4.93, 4.35-5.51), and 40-49 (4.86, 4.04-5.69); findings were driven largely by PTC incidence. For FTC, incidence was stable or decreased except for NH-blacks ages 30-39 (3.30, 0.26-6.43) and 40-49 (3.67, 1.22-6.18). Ten-year overall survival for PTC was similar or superior to that for FTC for each age decade. Findings observed for PTC and FTC incidence and survival tended to persist across racial/ethnic subgroups.
     
    Conclusion: Our findings confirm a continued increase in PTC incidence in US women ages 20-49. Over-diagnosis may be a less likely explanation of this trend, with routine imaging expected to occur less in younger than older women. Our findings, as well as other recent reports showing a rise in hormone receptor-positive breast cancer among pre-menopausal women, warrant investigations into environmental exposures, particularly estrogen exposures and endocrine disrupters, as potential causative factors for TC.

 

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