Racial disparities in overall survival after the introduction of cyclin-dependent kinase 4/6 inhibitors for patients with hormone receptor-positive, HER2-negative metastatic breast cancer

Abstract

Purpose: CDK4/6i combined with endocrine therapy have improved HR+/HER2-metastatic breast cancer (MBC) outcomes. However, it is still unclear whether the response to CDK4/6i is similar for all races. Therefore, we aimed to assess overall survival (OS) trends strati ed by race in patients with HR+/HER2-MBC after the approval of CDK4/6i, as part of the standard of care, in 2015.Methods: We performed a population-based study using the SEER database. Patients with HR+/HER2-MBC were divided into two time-based cohorts: 1) 2011-2013, corresponding to the pre-CDK4/6i era, and 2) 2015-2017 to the post-CDK4/6i era. We used propensity score matching and identi ed 2,684 patients in each cohort that matched in several characteristics. Kaplan-Meier curves and Cox proportional hazard models were used to estimate 2-year OS.Additionally, we compared survival between groups with a strati ed log-rank test. Lastly, we compared OS and breast cancer death risk between cohorts (strati ed by race) using Fine and Gray model. Results:The 2-year OS rate was 65% for the post-CDK4/6i group and 62% for the pre-CDK4/6i cohort (strati ed logrank p=0.025). The 2-year OS for NHW patients improved in the post-CDK4/6i era compared to the pre-CDK4/6i era (67% vs. 63%, p=0.033). However, OS did not improve for NHB (54% vs. 54%, p=0.876) or Hispanic (67% vs 65%, p=0.617) groups.Conclusions: Our study con rms that outcomes for HR+/HER2-MBC have improved after CDK4/6i were introduced in 2015. However, this effect is primarily driven by the improved OS in NHW patients, without signi cant improvement in OS in NHB or Hispanics.

Multiplex Imaging Reveals Novel Subcellular, Microenvironmental, and Racial Patterns of MRTFA/B Activation in Invasive Breast Cancers and Metastases

“…Breast cancer claims the lives of over 43,000 women in the United States each year and the vast majority of breast cancer-related deaths result from distant metastases 1,2 . Unfortunately, there are very few treatment options for women diagnosed with metastatic breast cancer and some existing therapeutic strategies are even less effective in prolonging the lives of vulnerable patient populations, such as African American women, who are more likely to die from breast cancer than women from other racial groups 1,3,4 . This survival disparity is caused by structural racism and social determinants of health, which are thought to foster a chronic level of elevated stress that, in turn, influences tumor evolution, promotes an inflammatory microenvironment and leads to metastases 5–7 .…”