Resident Physician Walkout and High-Incidence Cancer Operation Volumes in South Korea

Importance Resident physicians constitute a small proportion of South Korea’s physician workforce overall but nearly one-third of staff at tertiary hospitals, where they provide essential frontline care. Their absence may jeopardize access to time-sensitive treatments, such as cancer operations. Objectives To assess the association of the 2024 resident physician walkout in South Korea with operation volumes for 6 common cancers and evaluate whether general hospitals absorbed displaced cases. Design, Setting, and Participants This cross-sectional study with an interrupted time-series analysis used segmented regression of monthly claims data from the Health Insurance Review and Assessment Service from January 1, 2019, to December 31, 2024, representing nationwide inpatient surgical volumes. All tertiary and general hospitals in South Korea that submitted operation claims for colorectal, gastric, liver, lung, breast, and thyroid cancer identified using diagnosis and procedure codes were included. Exposure Mass resignation of more than 10 000 resident physicians beginning in February 2024. The intervention point was March 2024. Main Outcomes and Measures Monthly operative claims for each cancer type, stratified by hospital level. Negative binomial regression estimated immediate (level) and slope changes. Results This study analyzed 652 681 claims for operations for 6 high-incidence cancers over the 6-year study period, representing nationwide inpatient surgical volumes. Among these claims, tertiary hospitals showed immediate decreases for colorectal (incidence rate ratio IRR, 0.78; 95% CI, 0.70-0.86; P lt; .001), gastric (IRR, 0.77; 95% CI, 0.66-0.88; P lt; .001), lung (IRR, 0.68; 95% CI, 0.61-0.76; P lt; .001), breast (IRR, 0.80; 95% CI, 0.72-0.88; P lt; .001), and thyroid cancer (IRR, 0.68; 95% CI, 0.60-0.77; P lt; .001) operations, but not liver cancer (IRR, 0.93; 95% CI, 0.85-1.01; P = .08). General hospitals showed increases for gastric (IRR, 1.33; 95% CI, 1.16-1.52; P lt; .001), lung (IRR, 1.32; 95% CI, 1.17-1.49; P lt; .001), and breast cancer (IRR, 1.42; 95% CI, 1.27-1.57; P lt; .001) operations. General hospitals absorbed approximately 58% of breast cancer operations but only 16% to 25% of colorectal, gastric, and lung cancer operations, resulting in a net nationwide decrease. Conclusions and Relevance In this cross-sectional study with an interrupted time-series analysis of national claims data, the 2024 resident physician walkout in South Korea was associated with substantial reductions in cancer operations at tertiary hospitals, which were only partially compensated by general hospitals. These findings highlight the structural vulnerability of South Korea’s health care system, arising from an overreliance on resident physicians.