Disparities in Early-Stage Breast Cancer and Survival—Letter

We commend Primm and colleagues for performing an analysis of ethnoracial disparities in outcomes in women with early-stage breast cancer (1). As the authors note, aggregating race/ethnicity into broad categories may mask important differences between different ethnoracial subgroups. This study was more comprehensive than prior studies in that individuals who identified as Pacific Islander had their own category. In addition, the authors disaggregated those identifying as Asian into four distinct subgroups.

With respect to ethnicity, the Hispanic population is an extremely diverse ethnoracial group that represents the fastest growing demographic in the United States. Therefore, while we completely agree with Primm and colleagues about the disaggregation of Asian people we would argue those of Hispanic ethnicity also warrant the same level of ethnoracial granularity. Studies in patients with breast cancer have demonstrated that disaggregating Hispanic ethnicity by race captures ethnoracial (Hispanic White, Hispanic Black, etc.) differences in stage, treatment, and survival not elucidated by aggregating Hispanic individuals into one group (2, 3). Consequently, we encourage the authors to conduct further analysis examining the study endpoints with the disaggregation of the Hispanic population by race. We anticipate this approach will help delineate the influence of race and ethnicity on the trend towards worse survival outcomes seen in Hispanic people with early-stage disease and across subtypes (except triple-negative disease). With respect to triple-negative disease, it would be particularly interesting to see if there are survival differences in Black people based on Hispanic ethnicity. Paradoxically, Hispanic individuals with stage IIIB-IV disease had improved survival relative to non-Hispanic White individuals, but again, it is critical to understand if this disparity is driven by ethnoracial differences in Hispanic patients. Of note, prior studies using SEER have successfully disaggregated Hispanic ethnicity by race (4).

In addition to disaggregating ethnicity by race, categorizing Hispanic people by country of origin is also important when possible. SEER does collect birthplace information, but there is a high level of missing data and the veracity of the datapoint is in question (5). While acknowledging that Hispanic people were not differentiated further as a limitation, the authors do not provide contextual information for readers as to why this limitation is important. For example, in patients with pancreatic cancer, investigators have shown that among Hispanic individuals, Dominicans and South/Central Americans had the best survival rates (6).

In summary, we agree that contemporary analyses of race and ethnicity needs improvement with as many distinct categories as possible to reflect the diversity of the patient population. We believe that Hispanic patients should be categorized by both race and ethnicity. When feasible, investigators should also report country origin for foreign born individuals of any race and/or ethnicity. Granular ethnoracial categories will help improve our understanding of the independent and synergistic effects of ethnicity and race on cancer outcomes.

See the Response, p. 1868