Racial inequities in second-line treatment and overall survival among patients with metastatic breast cancer.

BACKGROUND

Black women in the USA have a higher incidence and mortality of metastatic breast cancer (mBC) than White women, while Hispanic women have lower rates. Previous studies have focused on first-line (1L) treatment, but little is known about racial differences in treatment beyond 1L and their impact on outcomes.

METHODS

This analysis utilized data from an electronic health record derived de-identified database and included patients with HR+HER2- mBC initiating 2L treatment (including CDK4/6-inhibitor [CDKi]-based, endocrine monotherapy, everolimus combination therapy, and chemotherapy and other systemic therapies) between 2/3/2015 and 7/31/2021. Real-world overall survival (rwOS) was defined as time from 2L initiation to death. Multinomial logistic regression assessed the likelihood of 2L treatment between race/ethnicity groups. Median rwOS was estimated using the Kaplan-Meier method and adjusted hazard ratios were estimated using multivariable Cox proportional hazards models.

RESULTS

Among all patients who received 2L, non-Hispanic Black (NHB) and Hispanic/Latino patients were less likely to receive 2L CDKi compared to non-Hispanic White (NHW) patients (36%, 39% vs 42%, respectively). Median rwOS was 20.4, 37.6, and 25.3 months, in NHB, Hispanic/Latino and NHW patients, respectively. The rwOS remained poorer among NHB patients after adjustment (HR = 1.16; p = 0.009). In stratified analysis, adjusted rwOS was similar between NHB and NHW patients among those who received 1L CDKi.

CONCLUSIONS

These findings suggest that among patients with HR+HER2- mBC, NHB patients had worse survival beyond front-line setting, mainly among the subset of women who did not receive CDKi at 1L. This inequities in rwOS between race/ethnicity groups was not observed among patients who received 1L CDKi.