Social Vulnerability Association with Thyroid Cancer Disparities in the United States

Background: As thyroid cancer (TC) incidence rises, it is increasingly valuable to recognize disparities in treatment and diagnosis. Prior investigations in social determinants of health are limited to pediatric populations or studies looking at single factors such as race or environmental influences. Utilizing the CDC-Social Vulnerability Index (SVI) and SEER-patient database, to assess the amalgamated, real-world influence of varied social determinants of health (SDoH) and their quantifiable impact on TC-disparities across the United States (US). Methods: In a retrospective cohort study, 199,340 adult TC patients from 1975-2017 were assessed for significant regression trends in months of follow-up/surveillance, survival, late-staging, and treatment receipt across TC-subtypes with increasing overall-social vulnerability, as well in 15 SDoH-variables regarding socioeconomic status (SES), minority-language status (ML), household-composition (HH), and housing-transportation (HT) across all United States (US) counties while accounting for sociodemographic-regional differences. Results: With increasing overall social vulnerability, decreases in months of follow-up were observed with patients with papillary, follicular, medullary, oncocytic, and anaplastic TC (p=0.001). Comparing lowest to highest-vulnerability cohorts, relative decreases in months-surveillance ranged from 55.6% (14.5 to 6.5 months) with anaplastic to 17% (108.6 to 90.2) with oncocytic. SES followed by HH & HT contributed to these overall trends. Similar survival decreases occurred across all TC, ranging from 55.9% (9.6 to 4.2) with anaplastic to 28.3% (97 to 69.5) with oncocytic, mainly contributed by ML and HT. Increasing overall vulnerability was associated with increased odds of advanced-staging for papillary (OR, 1.07; 95% CI, 1.03-1.12) and decreased odds of indicated treatment via surgery (lowest, medullary: 0.91; 0.84-0.99), radiation therapy (lowest, anaplastic: 0.88; 0.82-0.93), and chemotherapy (lowest, oncocytic: 0.81 0.67-0.98) were observed; ML, HT followed by SES were contributors to these overall vulnerability trends. Conclusions: Our results show significant detriments in TC care & prognosis in the US with increasing overall social vulnerability while identifying which SDoH quantifiably contribute more to disparities in interrelational, real-world-like contexts.