Female Breast Cancer Incidence and Association with Socioeconomic Status in a Population-Based Cohort - China, 2018-2024

Introduction: Breast cancer has emerged as the most prevalent cancer among women globally. However, the relationship between individual socioeconomic status (SES) and breast cancer risk remains incompletely understood. Methods: This population-based cohort study recruited women aged 30-70 years from Shandong, Hebei, and Jiangsu provinces in China during 2008 and 2018. We developed a composite SES measure through latent class analysis incorporating household income, education level, and health insurance type, stratifying participants into low and high SES groups. Self-perceived SES was evaluated using a Likert scale. We employed Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between SES and breast cancer incidence. Results: Among 62,350 participants followed for an average of 6.1 person-years, we identified 300 incident breast cancer cases. The overall incidence rate was 48.9 per 100,000 person-years. Women with high SES demonstrated significantly elevated breast cancer risk compared to those with low SES (HR=1.42, 95% CI: 1.05-1.92). Self-perceived SES appeared to modify this relationship, with increased breast cancer risk observed among women categorized as both objectively and subjectively low SES. Conclusions: These findings underscore the need for SES-specific approaches to breast cancer screening programs and targeted health education initiatives.