A Contemporary Analysis of Racial and Ethnic Disparities in Diagnosis of Early-Stage Breast Cancer and Stage-Specific Survival by Molecular Subtype

Background: Prior studies of breast cancer disparities have focused primarily on differences between Black and White women, yet contemporary patterns of disparity for other groups are not well understood. We examine breast cancer disparities by stage at diagnosis across nine racial and ethnic groups. Methods: The SEER 18 registries identified 841,975 women diagnosed with breast cancer from 2000 to 2017. Joinpoint models assessed trends in diagnosis stage and survival. Multivariable logistic regression evaluated associations between race/ethnicity and diagnosis stage. Multivariable Cox models compared survival of groups by stage and molecular subtype. Results: Black, American Indian, Southeast Asian, South Asian, Pacific Islander, and Hispanic women were less likely than white women to be diagnosed with early stage breast cancer. Among those diagnosed at early stage, Hispanic, American Indian, Pacific Islander and Black women were 9%, 14%, 22%, and 39% (respectively) more likely than White women to die from breast cancer, whereas Asian subgroups had lower risk of death. Among those diagnosed at late stage, Black women were 18% more likely than White counterparts to die from breast cancer, and survival disparities for Black women persisted across all subtypes and stages, (except late stage HR^-/HER2^-). East Asian women with early stage HR⁺/HER2^- tumors had better survival than White women. Conclusions: Persistent disparities in early detection and survival of breast cancer demand further work to address and reduce disparities across the cancer continuum. Impact: Results have implications for efforts to reduce entrenched racial and ethnic disparities in breast cancer early detection and survival.