Race and Socioeconomic Status are Predictors of Survival in Patients With Metastatic Bone Disease Secondary to Breast Cancer

Abstract

Background

With implementation of early detection screening methods and advances in medical treatment, there have been improvement in outcomes for patients with breast cancer. Despite this, studies have suggested potential differences in outcomes amongst various racial and ethnic groups. To our knowledge, no study has evaluated if race and demographic characteristics impact survival outcomes in patients with breast cancer metastases to the bone.

Aims

We sought to answer the following questions: (1) Does race, demographic, and tumor characteristics alter survival outcomes in patients with breast metastases to the bone? (2) When stratifying by income and treatment, does race influence survival outcomes in patients with breast metastases to the bone?

Methods and Results

The surveillance, epidemiology, and end results (SEER) 2016 to 2021 database was reviewed for patients with a diagnosis of breast cancer with metastases to the bone N = 11 833. Patients with known primary breast cancer, known hormone receptor status, known metastasis to bone, known treatment regiment, and no additional cancer diagnoses were included. Using variables within the database, this study collected information on demographics and tumor characteristics. Multivariate analyses were conducted to determine associations between race and other demographic, clinical, and prognostic factors. Kaplan–Meier survival curves were utilized to evaluate outcome by race. Annual household income below $75 000 (hazard ratio 1.111 [95% confidence interval (CI): 1.047–1.178, p < 0.001]), age over 65 years old (hazard ratio 1.1150 [95% CI: 1.084–1.220, p < 0.001]), and race (black) (hazard ratio 1.256 [95% CI: 1.161–1.359, p < 0.001]) were independent risk factors for decreased survival likelihood. Surgery (hazard ratio 0.554 [95% CI: 0.507–0.606, p < 0.001]), chemotherapy (hazard ratio 0.421 [95% CI: 0.397–0.446, p < 0.001]), and radiation (hazard ratio 0.940 [95% CI: 0.885–0.998, p < 0.05]), were independent factors that increased survival. At 12-month follow-up (hazard ratio 1.211 [95% CI: 1.091–1.345, p < 0.001]) and 5-year follow-up (hazard ratio 1.256 [95% CI: 1.161–1.359, p < 0.001]) black women had decreased survival likelihood compared to all other races. When patients were stratified by annual household income greater than $75 000, regardless of treatment, black women had decreased survival likelihood in patients younger then 65 years old (hazard ratio 1.242 [95% CI: 1.117–1.381, p < 0.001]) and 65 years and older (hazard ratio 1.318 [95% CI: 1.121–1.550, p = 0.001]). Increasing age, race, and lower annual household income were significantly associated with higher mortality. When controlling for higher income and treatment variables, black women had significantly higher mortality rates at 5-year follow up.

Conclusion

Despite improved treatment methods, disparities among patients with metastatic breast cancer to bone exists. Our findings demonstrate that different sub-groups experience different mortality rates. Further research must be conducted to understand the interplay between these socioeconomic variables and survival likelihood in metastatic breast cancer.