Effects of Socioeconomic Status and Race on Survival and Treatment in Metastatic Breast Cancer

Background: Race and socioeconomic factors affect outcomes in breast cancer. We aim to assess the effect of race and neighborhood socioeconomic status (SES) on overall survival and treatment patterns in patients with metastatic breast cancer (MBC) Method: Retrospective cohort study involving patients (N = 1,246) with distant breast cancer metastases diagnosed at UPMC Magee Women’s Breast Cancer Clinic from 2000–2017. Overall survival and treatment patterns were compared between races (African Americans and Caucasians) and SES groups (defined using National Deprivation Index) Results: Low SES, but not tumor characteristics, was associated with African American race (P P = .01) and African American race (Median [IQR] survival 1.8[1.3–2.3] years, vs Caucasians 2.5[2.3–2.7] years P = .008) separately predicted worse overall survival in patients with MBC. In the Cox Proportional Hazard model with SES, race, age, subtype, and number of metastases as covariates, low SES (Hazard ratio 1.19[1.04–1.37], P = .01), but not African American race (Hazard ratio 1.23[0.97–1.56], P = .08), independently predicted overall survival in MBC. Moreover, patients with ER + MBC from low SES neighborhoods were more likely to be treated with tamoxifen than aromatase inhibitors+/-newer agents, and African Americans received fewer lines of chemotherapy than Caucasians. Conclusions: Low neighborhood SES is associated with worse outcomes in patients with MBC. Poor outcomes in African American patients with MBC, at least in part is driven by socioeconomic factors. Future studies should delineate the interplay between neighborhood SES, race, and their effects on tumor biology in MBC.