Socioeconomic Disparities in Six Common Cancer Survival Rates in South Korea: Population-Wide Retrospective Cohort Study

Background: In South Korea, the cancer incidence rate has increased by 56.5% from 2001 to 2021. Nevertheless, the 5-yearcancer survival rate from 2017 to 2021 increased by 17.9% compared with that from 2001 to 2005. Cancer survival rates tendto decline with lower socioeconomic status, and variations exist in the survival rates among different cancer types. Analyzingsocioeconomic patterns in the survival of patients with cancer can help identify high-risk groups and ensure that they benefitfrom interventions.Objective: The aim of this study was to analyze differences in survival rates among patients diagnosed with six types ofcancer-stomach, colorectal, liver, breast, cervical, and lung cancers-based on socioeconomic status using Korean nation-wide data.Methods: This study used the Korea Central Cancer Registry database linked to the National Health Information Databaseto follow up with patients diagnosed with cancer between 2014 and 2018 until December 31, 2021. Kaplan-Meier curvesstratified by income status were generated, and log-rank tests were conducted for each cancer type to assess statisticalsignificance. Hazard ratios with 95% CIs for any cause of overall survival were calculated using Cox proportional hazardsregression models with the time since diagnosis.Results: The survival rates for the six different types of cancer were as follows: stomach cancer, 69.6% (96,404/138,462);colorectal cancer, 66.6% (83,406/125,156); liver cancer, 33.7% (23,860/70,712); lung cancer, 30.4% (33,203/109,116); breastcancer, 91.5% (90,730/99,159); and cervical cancer, 78% (12,930/16,580). When comparing the medical aid group to thehighest income group, the hazard ratios were 1.72 (95% CI 1.66-1.79) for stomach cancer, 1.60 (95% CI 1.54-1.56) forcolorectal cancer, 1.51 (95% CI 1.45-1.56) for liver cancer, 1.56 (95% CI 1.51-1.59) for lung cancer, 2.19 (95% CI 2.01-2.38)for breast cancer, and 1.65 (95% CI 1.46-1.87) for cervical cancer. A higher deprivation index and advanced diagnostic stagewere associated with an increased risk of mortality.Conclusions: Socioeconomic status significantly mediates disparities in cancer survival in several cancer types. This effectis particularly pronounced in less fatal cancers such as breast cancer. Therefore, considering the type of cancer and socioeco-nomic factors, social and medical interventions such as early cancer detection and appropriate treatment are necessary forvulnerable populations