Within-Region Versus Out-of-Region Cancer Care: Healthcare Patterns and Clinical Outcomes in South Korea.

Background/Objectives: Patient concentration in high-volume tertiary hospitals in the capital region of South Korea has become a major health policy concern. We examined the associations of out-of-region cancer care with healthcare utilization, healthcare expenditure, and clinical outcomes. Methods: We included 303,443 patients newly diagnosed with one of six major cancers between 2012 and 2020 using the Cancer Public Library Database of the Korea Clinical Data Utilization Network for Research Excellence project. Out-of-region cancer care was defined as initial treatment received outside the patient's residential region. Multivariable regression models evaluated healthcare utilization, healthcare expenditure, and clinical outcomes. Sensitivity analyses considered pretreatment care-seeking fragmentation, and subgroup analyses were performed by cancer stage. Results: Out-of-region cancer care was associated with higher healthcare expenditure (relative risk [RR], 1.02; 95% confidence interval [CI], 1.02-1.03), delayed treatment initiation (odds ratio [OR], 1.19; 95% CI, 1.15-1.22), and lower 1-year (hazard ratio [HR], 0.88; 95% CI, 0.84-0.92) and 5-year (HR, 0.93; 95% CI, 0.91-0.96) all-cause mortality. A modest association with increased emergency department visits was observed in the main analysis (HR, 1.03; 95% CI, 1.01-1.07), although this association was not robust in the sensitivity analyses. These associations with healthcare utilization were stronger among patients with pretreatment care-seeking fragmentation and those with localized or regional cancer. Conclusions: Out-of-region cancer care was associated with lower mortality but higher healthcare utilization. Strengthening regional cancer care capacity and coordinated referral pathways may improve continuity of care while ensuring equitable access to specialized cancer services.