Contrasting income-based inequalities in incidence and mortality of breast cancer in Korea, 2006-2015.

Objectives: Breast cancer incidence and mortality rates in Korea are increasing. This study analyzed income-based inequalities in the incidence and mortality of women breast cancer from 2006 to 2015, using national data that covered all Korean women.

Methods: We used the National Health Information Database from 2006 to 2015. For women aged 20 and older, the age-standardized incidence and mortality rates of breast cancer per 100,000 by income quintile per year were calculated using the direct method. The rate ratio and rate difference (RD) of the age-standardized incidence and mortality rates of breast cancer per 100,000 between the top and bottom income quintiles were calculated as relative and absolute measures for inequalities.

Results: When comparing 2006 and 2015, both the incidence and mortality rates of breast cancer increased. The lowest income quintile experienced higher mortality rates despite having lower incidence rates. In 2015, the income-based RD in incidence and mortality rates between the highest and lowest income quintiles (Q1-Q5) was -19.9 (95% confidence interval [CI], -24.3 to -15.5) and 4.4 (95% CI, 2.9 to 5.8), respectively. Throughout this period, there was no statistically significant trend in income-based disparities in breast cancer incidence and mortality. The age-specific contributions to the absolute magnitude of inequality (RD) in incidence and mortality were more pronounced among middle-aged women than among older women.

Conclusions: This study found that breast cancer in Korea exhibited pro-rich inequalities in mortality despite pro-poor inequalities in incidence. More equitable policies for screening and treatment of breast cancer are needed.