Income Inequalities in Breast Cancer Survival Among Formally Employed Women in Colombia: A Cohort Study

PURPOSE Breast cancer is the most frequently diagnosed malignancy among women worldwide and a leading cause of cancer-related mortality. Income-related disparities in breast cancer survival are well documented in both high- and low- and middle-income countries. In Colombia, although formally employed women benefit from universal health care coverage, significant income disparities persist, potentially affecting timely diagnosis, treatment access, and survival outcomes. This study aimed to evaluate the association between income, measured in monthly minimum wages (MMW), and 5-year overall survival among formally employed women diagnosed with breast cancer in Colombia. PATIENTS AND METHODS We conducted a retrospective cohort study using national administrative databases to evaluate the association between income and 5-year survival in women diagnosed with breast cancer between January 1, 2013, and June 30, 2018. Breast cancer diagnosis was confirmed through an algorithm requiring at least three International Classification of Diseases, 10th Revision codes across different months and one oncologic procedure. Income at diagnosis was expressed in legal MMW units and categorized into quartiles. Covariates included age, cancer stage, Charlson Comorbidity Index, region, insurer, and year of diagnosis. Follow-up lasted up to 5 years or until death. Survival analyses used Cox regression models to estimate hazard ratios (HRs) with 95% CIs. Relative Index of Inequality (RII) and Slope Index of Inequality (SII) were also estimated using Poisson regression. RESULTS A total of 3,352 formally employed women with breast cancer were included, with a mean age at diagnosis of 46.59 years. Income levels for the 25th, 50th, and 75th percentiles were 1.00, 1.43, and 2.76 MMW, respectively. Over the 5 years, 511 deaths were recorded (15.24% mortality). After adjustment for confounders, women in the highest income quartile had a 26% lower risk of death compared with those in the lowest quartile (adjusted HR, 0.74 95% CI, 0.57 to 0.95). RII and SII further confirmed significant income-related disparities in survival outcomes. CONCLUSION Among formally employed women in Colombia, income disparities are significantly associated with breast cancer survival. These findings suggest that structural, economic, and regional barriers persist in delivering optimal cancer care.