Metastatic breast cancer at initial diagnosis in the United States: Racial differences in prevalence, clinical characteristics, and survival

Distant metastases at initial diagnosis signifiy important causes of morbidity and leads to a higher mortality among patients with breast cancer. Racial disparities in cancer management have been well documented but estimates of racial differences in metastatic breast cancer at initial diagnosis are lacking. We obtained data using the publicly available database of Surveillance, Epidemiology, and End Results Program (SEER) to export data from SEER Research Database (8 reg; Nov 2021 Submission) for women diagnosed with breast cancer between 1975 and 2019. Data including race, age at diagnosis, summary stage, and survival were exported for analysis in SPSS. Between 1975 and 2019, 294,886 cases were diagnosed with breast cancer (25,405, 234,415, and 35,066 of black, white, and other races, respectively). In total, 15,779 cases had distant metastasis at time of initial diagnosis. Black patients had a significantly higher prevalence of metastatic disease at initial diagnosis (8.5%, 5% and 5.1% in black, white, and other races, respectively, P<0.001). An exploratory analysis of age distribution revealed a higher prevalence of early-onset breast cancer in black patients compared to other groups (Table). Black patients with metastatic breast cancer had a significantly shorter mean overall survival months (27.1, 32.7, and 32.5 for black, white, and other races respectively, P<0.001), and a significantly higher cancer-specific mortality rate (72.4%, 70.2% and 65.3% in black, white, and other races, respectively, P<0.001).Table: 1324PAge of diagnosis for patients with metastatic breast cancer at initial diagnosis for different racesBlackWhiteOtherP value (χ2)Post hoc (Adjusted standardized residuals)< 50 Years625 (28.9%)2079 (17.6%)447 (25.1%)< 0.001Black > Other > White50 – 59 Years576 (26.6%)2559 (21.6%)494 (27.8%)Other > Black > White60 – 69 Years531 (24.5%)3066 (25.9%)289 (21.9%)Other > Black = White70 – 79 Years278 (12.8%)2239 (18.9%)253 (14.2%)White > Other > Black≥ 80 years156 (7.2%)1891 (16%)196 (11%)White > Other > Black Open table in a new tab Among women with metastatic breast cancer at initial diagnosis, substantial racial differences exist, with black patients having higher prevalence, younger age at diagnosis and shorter overall survival. While genomic profiles maybe a factor driving such difference, disparities in healthcare access may contribute to the highlighted disparities in prevalence and outcomes.