Socioeconomic Inequalities in Stomach Cancer Screening in Korea, 2005-2015: After the Introduction of the National Cancer Screening Program

Abstract

Purpose: This study aimed to investigate socioeconomic inequalities in stomach cancer screening in Korea and trends therein across income and education groups.

Materials and methods: Data from the Korean National Cancer Screening Survey, a nationwide cross-sectional survey, were utilized. A total of 28913 men and women aged 40 to 74 years were included for analysis. Prior experience with stomach cancer screening was defined as having undergone either an endoscopy or gastrointestinal series within the past two years. The slope index of inequality (SII) and relative index of inequality (RII) were evaluated to check inequalities.

Results: Stomach cancer screening rates increased from 40.0% in 2005 to 74.8% in 2015, with an annual percent change of 5.8% [95% confidence interval (CI) 4.2 to 7.5]. Increases in stomach cancer screening rates were observed for all age, education, and household income groups. Inequalities in stomach cancer screening were noted among individuals of differing levels of education, with a pooled SII estimate of 6.14% (95% CI, 3.94 to 8.34) and RII of 1.26 (95% CI, 1.12 to 1.40). Also, income-related inequalities were observed with an SII of 6.93% (95% CI, 4.89 to 8.97) and RII of 1.30 (95% CI, 1.17 to 1.43). The magnitude of inequality was larger for income than for education.

Conclusion: Both education and income-related inequalities were found in stomach cancer screening, despite a continuous increase in screening rate over the study period. Income-related inequality was greater than education-related inequality, and this was more apparent in women than in men.

Keywords: Stomach neoplasm; early detection of cancer; inequalities; mass screening.

Fig. 1. Absolute and relative inequalities in stomach cancer screening from 2005 to 2015. (A) Absolute educational inequalities in stomach cancer screening rates. (B) Relative educational inequalities in stomach cancer screening rates. (C) Absolute household income inequalities in stomach cancer screening rates. (D) Relative household income inequalities in stomach cancer screening rates. Solid line represents the line of equality; dotted line reflects pooled coefficients. SII, slope index of inequality; RII, relative index of inequality; CI, confidence interval.