Abstract 3595: Estimating excess mortality due to cancer during the COVID-19 outbreak in South Korea

Abstract Background: Excess mortality serves as a valuable metric for evaluating the comprehensive health impact of healthcare systems worldwide during the COVID-19 pandemic, particularly affecting vulnerable populations, including cancer patients. This study aims to estimate excess mortality attributable to all causes and cause-specific mortality, including cancer, during the COVID-19 pandemic in South Korea. Methods: Monthly mortality data from January 2000 to December 2022 was obtained from Statistics Korea. Using the World Health Organization International Classification of Diseases and Related Health Problems (ICD-10), we identified deaths due to neoplasia (C00-D48), infectious diseases (A00-B99, U07.1, U07.2, U10), cardiovascular diseases (I00-I99), and respiratory diseases (J00-J98, U04). Excess mortality during 2020-2022 was calculated by subtracting the predicted monthly number of deaths from the observed deaths from January 2020 to December 2022. The predicted number of deaths in 2020-2022 was estimated by using exponential smoothing, specifically, Error-Trend-Seasonal (ETS) models based on the death in 2000-2019. AIC, BIC and Log likelihood criteria were used to evaluate the different models of ETS, which showed that (additive, additive, additive) model was the most well-fitting. Results: All-cause excess mortality was highest in March 2022, with a total of 44, 616 observed deaths (predicted deaths: 26, 874, 95% confidence interval (CI): 22, 271 - 31, 476 deaths, statistically significant). There was significant excess mortality due to infectious and parasitic diseases in every month from 2021 to 2022, peaking at March 2022 (1367.75%), which corresponded to 11, 893 observed deaths (predicted deaths: 810, 95% CI 676 - 945). The number of deaths attributable to cardiovascular or respiratory diseases was not statistical different from predicted values. Notably, excess mortality attributable to cancer was significantly associated with the COVID-19 pandemic, peaking in February 2022 at a rate exceeding 4.45%, equating to 6, 740 observed deaths (predicted deaths: 6453, 95% CI 6212 - 6704). Among those deaths, males experienced a higher excess mortality rate of 3.91%, compared to 1.74% among females. Conclusion: We observed a significant overall increase in all-cause excess mortality during 2022 in South Korea related to the COVID-19 outbreak. Although cancer deaths remained relatively stable and closely aligned with predicted values during the study period, there was 4.45% increase of cancer death in 2022 February which exceeded the upper limit of 95% CI. Our study provides valuable insights into the resilience of cancer-related mortality patterns in South Korea amidst the challenges posed by the pandemic in accessing healthcare services and medical resources. Citation Format: Linh Thi My Bui, Jinwoo Cho, Yun-Chul Hong, Yoon-Jung Choi. Estimating excess mortality due to cancer during the COVID-19 outbreak in South Korea [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3595.