The contribution of rural/urban residence to incidence and survival in thymoma and thymic carcinoma, a retrospective cohort study of the SEER 2000-2020 database

Abstract

Objective: Rural-urban healthcare disparities have been demonstrated throughout the United States, particularly in acquiring oncologic care. In this study, we aim to discern the role of rural-urban health disparities in thymic cancer incidence and uncover potential survival disparities.

Methods: The Surveillance, Epidemiology, and End Results (SEER) 17-State database was queried for all cases of thymoma (ICD-O-3/3 codes: 8580-8585) and thymic carcinoma (8586) located in the thymus (primary site code C37.9) diagnosed between 2000 and 2020. Residence was established using SEER Rural-Urban Continuum Codes. Incidence trend modeling for rural versus urban patients was completed using Joinpoint Regression Software. Chi-square, Kaplan-Meier with log-rank testing, and Cox proportional hazards was completed using SPSS, with significance set to p <0.05.

Results: Joinpoint analysis revealed a significant growth in incidence in the urban population compared to a stagnant incidence among the rural population. Disease specific survival was higher among urban patients on univariate modeling (p = 0.010), and confirmed on multivariate analysis, whereby rural living conferred an adjusted hazard ratio of 1.263 (95 % CI 1.045-1.527; p = 0.016) in comparison to urban patients.

Conclusions: These findings demonstrate differences between thymic cancer incidence and outcomes in patients living in urban versus rural environments and demonstrate an important disparity.

Keywords: SEER database; Survival outcomes; Thymic carcinoma; Thymoma.