The impact of socioeconomic status on the use of adjuvant radioactive iodine for papillary thyroid cancer

Introduction: The effect of socioeconomic status (SES) on thyroid cancer treatment has not been studied extensively. The purpose of this study is to determine the impact of SES on the use of adjuvant radioactive iodine (RAI) after total thyroidectomy for papillary thyroid cancer (PTC). We hypothesize that patients of low SES are less likely to receive RAI after total thyroidectomy. Methods: Case characteristics of 9011 patients with PTC ≥1cm in size and undergoing total thyroidectomy were extrapolated from the Surveillance, Epidemiology and End Results database. Chi-square test and multivariate analyses were performed to compare demographics, clinicopathologic features, and use of RAI by county-level measures of SES. Results: Low-SES patients were more likely to present with positive lymph nodes in the <45-year age group and with advanced American Joint Committee on Cancer stage, positive lymph nodes, multifocal tumors, extrathyroidal extension, and larger tumors in the ≥45-year age group. Among patients <45 years of age, those from counties with a higher median household income and a higher SES composite score had significantly higher rates of RAI use (odds ratio [OR] 1.36, [95% confidence interval (CI) 1.09-1.70], p=0.006, and OR 1.29 [CI 1.11-1.49], p<0.001, respectively). Among patients ≥45 years of age, those residing in counties with higher education levels were associated with higher rates of RAI use (OR 1.27 [CI 1.05-1.54], p=0.015), while the association between SES composite score and RAI use approached statistical significance (OR 1.13 [CI 1.00-1.28], p=0.053). Conclusions: This study demonstrates that low SES is associated with more advanced PTC at presentation and a lower rate of adjuvant RAI after total thyroidectomy, particularly among patients <45 years of age from areas with a low median household income. Future studies are needed to address these disparities, as well as to determine appropriate indications for the use of adjuvant RAI for PTC.