Geographic access to triple negative breast cancer clinical trials: are trials located near patients?

Abstract

Background: Geographic proximity to clinical trials is a major barrier to trial participation, but geographic access to trials has not been specifically characterized for triple-negative breast cancer (TNBC). We evaluated the geographic distribution of TNBC treatment trials across U.S. counties and examined associated social and demographic characteristics.

Methods: All trials registered on ClinicalTrials.gov as of September 30, 2024 (n = 510,397) were queried, and active phase II and III TNBC treatment trials were identified through keyword searches. County-level population estimates from the 2018-2022 U.S. Census Bureau 5-year estimates and county adjacency data were used to evaluate trial availability and geographic access. Trial availability was examined according to sponsorship, rurality, health vulnerability, race and ethnicity, and U.S. region.

Results: We identified 108 active TNBC trials, including 58 (54%) for metastatic and 50 (46%) for non-metastatic disease. Overall, 76% of U.S. counties had no TNBC trials, 12% had exclusively federally sponsored trials, 10% had both federally and non-federally sponsored trials, and 2% had only non-federally sponsored trials. Trial availability was significantly lower in counties with the highest health vulnerability and in rural counties, which were more likely to rely exclusively on federally sponsored trials. Counties with predominantly Black, Hispanic, and American Indian and Alaska Native populations were less likely to have TNBC trials than predominantly non-Hispanic White counties. Women in the South were more likely than women in the Northeast to have no TNBC trial available in either their county of residence or a neighboring county.

Conclusions: TNBC clinical trials are geographically concentrated across the United States, with substantial disparities in access affecting rural and highly vulnerable counties, counties with predominantly racial and ethnic minority populations, and women living in the South. Federally sponsored trials may play an important role in supporting trial availability in underserved areas. Expanding the geographic distribution of TNBC trials may help improve equitable access to clinical trial participation.