Dr Podany on Food Desert Residence, ctDNA Profiles, and Survival in Breast Cancer

A multi-institutional retrospective cohort study presented at the 2026 ASCO Annual Meeting found that patients with metastatic breast cancer (MBC) living in food deserts harbor distinct circulating tumor DNA (ctDNA) profiles and face significantly worse survival outcomes, with the greatest disparities observed among Black patients.

The study drew on ctDNA data from the Guardant360 assay across four academic medical centers — Washington University in St. Louis, Massachusetts General Hospital, Weill Cornell Medicine, and Northwestern University—comprising 851 patients with census tract data. Researchers linked patient addresses to the USDA Food Access Research Atlas, categorizing patients by low food access (LA) and by low-income plus low access (LILA).

Nearly half of patients (46.8%) lived in LA areas, while 8.0% lived in LILA areas. Although White patients were more likely than Black patients to live far from food stores (48.9% vs 34.4%), Black patients were disproportionately represented in LILA areas (19.2% vs 6.1%).

On multivariate analysis adjusted for race, stage, and subtype, LA residence was independently associated with a roughly twofold increased likelihood of RTK/RAS pathway mutations in the overall cohort (OR 2.05) and in the hormone receptor–positive, HER2-negative (HR+/HER2–) subgroup (OR, 2.18). Patients in LILA areas were nearly three times more likely to harbor CCNE1 copy number variants (OR, 2.81), a genomic alteration tied to poor prognosis and CDK4/6 inhibitor resistance.

Survival outcomes reflected these biological differences. Median overall survival after first ctDNA testing was significantly shorter for patients in LA areas compared with those in high-access areas (24 vs 31 months). Among patients with HR+/HER2– MBC, Black patients in LA areas fared worst, with a median overall survival of just 11 months, compared with 38 months for Black patients in high-access areas and 27–33 months for White patients regardless of food access.

The authors conclude that food desert residence is associated with more aggressive tumor genomics and worse survival in MBC, underscoring the importance of integrating social determinants of health into oncologic care and research frameworks.