Socioeconomic Status and Survival in Sarcomas of the Breast: Nationwide Cohort Study

INTRODUCTION: Socioeconomic status (SES) has been associated with survival in breast cancer; yet its role in sarcomas of the breast remains poorly studied. We aimed to investigate whether individual-level SES, approximated by educational attainment and household income, is associated with overall survival in a nationwide cohort of women with sarcomas of the breast within a universal healthcare system. METHODS: We conducted a nationwide cohort study by using linked Swedish population registers. Women diagnosed with an incident borderline or malignant phyllodes tumor (PT), angiosarcoma, or soft-tissue sarcoma of the breast from 1993 to 2018 were included and followed through 2019. Socioeconomic status was defined by highest attained education and household disposable income. The primary outcome was all-cause death. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated by using multivariable Cox proportional hazards regression. RESULTS: A total of 473 women were included (median age, 51 years). The cohort comprised 198 borderline PT, 179 malignant PT, 25 angiosarcomas, and 71 soft-tissue sarcomas. Median follow-up was 13.1 years. In multivariable analyses, educational level was not associated with overall survival (OS) (≤9 vs. >13 years, HR 1.29, 95% confidence interval [CI] 0.76-a2.22; 10-13 vs. >13 years, HR 1.16, 95% CI, 0.71-1.89]). Lower household income was associated with worse OS (Q1 vs. Q5, HR 2.35, 95% CI 1.22-4.52; Q2 vs. Q5, HR 1.98, 95% CI 1.06-3.7). CONCLUSIONS: Lower income, but not education level, was associated with worse OS in patients with sarcomas of the breast. These results underscore the presence of survival disparities among patients with rare breast tumors, even within a universal healthcare system.