The study, led by Emily L. Podany and Andrew A. Davis of Washington University in St. Louis together with collaborators at Weill Cornell Medicine, Northwestern University, and Massachusetts General Hospital, drew on clinical and genomic data collected between 2015 and 2024. All patients had metastatic breast cancer and had undergone liquid biopsy testing with the Guardant360 assay, which detects mutations, copy number changes, and gene fusions across dozens of cancer-related genes from a simple blood sample. To quantify neighborhood disadvantage, the team used the Area Deprivation Index, or ADI, a validated composite of seventeen measures including poverty, employment, and education, ranked nationally from 1 to 100 by nine-digit zip code. Patients scoring 60 or above were classified as living in high deprivation neighborhoods.

Of the 1,127 patients analyzed, 335, or 29.7 percent, lived in high deprivation areas. Black patients were more than three times as likely as White patients to reside in these neighborhoods, reflecting the deep entanglement of race and socioeconomic disadvantage in the United States. After adjusting for age, race, cancer subtype, sites of metastatic disease, treatment line, and other clinical variables, the researchers found that patients from high deprivation neighborhoods had roughly 49 percent higher odds of harboring TP53 mutations in their tumors. Conversely, they were significantly less likely to carry AKT1 mutations, an alteration typically enriched in slower-growing, lower-grade luminal tumors.

The TP53 gene encodes p53, often described as the guardian of the genome. In healthy cells, this tumor suppressor protein halts division when DNA is damaged, triggers repair mechanisms, and pushes irreparably damaged cells into programmed death. When TP53 is mutated, that safety net collapses, allowing abnormal cells to proliferate unchecked. Mutations in the gene appear in roughly 30 percent of breast cancers and are linked to higher tumor grade, more aggressive subtypes, and worse prognosis. The new findings echo earlier tissue-based studies that connected household income and socioeconomic deprivation to higher p53 mutation frequency, but they extend that evidence to a large, racially diverse cohort of metastatic patients using blood-based genomic profiling.

Intriguingly, patients in high deprivation neighborhoods were less likely to present with visceral, lymph node, or soft tissue metastases, which might ordinarily suggest less advanced disease. Yet their survival was shorter. The authors propose that TP53-mutated tumors may drive rapid, aggressive progression even at lower disease burden, potentially before the kind of metastatic crises that prompt urgent intervention. They also point to the compounding weight of social determinants of health: patients in deprived neighborhoods experience higher rates of food insecurity, sarcopenia, and chronic disease, all of which erode the physical resilience needed to tolerate intensive cancer treatment.

The study also uncovered a stark treatment gap. Among 136 patients with hormone receptor-positive, HER2-negative metastatic disease who carried activating PIK3CA mutations and were therefore eligible for PI3K inhibitor therapy, only 17.4 percent of those in high deprivation neighborhoods actually received the drugs, compared with 36.7 percent of patients in low deprivation areas. This disparity emerged despite equal rates of PIK3CA mutations across deprivation groups, meaning the biological eligibility for targeted therapy was the same. The gap points squarely at access, not biology, as the limiting factor.

PI3K inhibitors such as alpelisib, approved by the Food and Drug Administration in 2019, and related AKT pathway inhibitors such as capivasertib represent some of the most consequential advances in precision oncology for breast cancer. But these therapies are expensive, require genomic testing to identify eligible mutations, and are often available primarily at academic cancer centers concentrated in affluent regions. Prior research has shown that patients from disadvantaged neighborhoods travel longer distances for care, are less likely to enroll in clinical trials, more often lack private insurance, and experience longer treatment delays and higher rates of therapy discontinuation. The new data suggest these structural barriers now extend into the era of molecularly targeted medicine.

Survival differences were perhaps the most sobering result. Median overall survival from the time of circulating tumor DNA testing was 24 months for patients in high deprivation neighborhoods versus 28 months for those in low deprivation areas, a statistically significant difference. When the researchers stratified by race, the picture became even more stark: Black patients in high deprivation neighborhoods survived a median of just 15 months, compared with 25 months for Black patients in low deprivation areas and 28 months for White patients regardless of neighborhood. Notably, Black patients living in advantaged neighborhoods fared as well as White patients, indicating that neighborhood deprivation and race interact to produce the worst outcomes rather than race acting alone.

The authors caution that the study has limitations. All patients were treated at large academic medical centers, so the findings may not generalize to community hospitals or rural clinics. The Area Deprivation Index has been criticized for overemphasizing housing values, and a single time-point measure cannot capture the cumulative environmental exposures involved in carcinogenesis, which unfolds over years or decades. Because the analysis was exploratory, no correction for multiple statistical testing was applied. Still, the cohort’s geographic breadth, spanning catchment areas across multiple states, and its use of individual-level chart review and uniform genomic testing lend considerable strength to the conclusions.

The implications reach beyond oncology. If living in a deprived neighborhood is associated with a distinct mutational landscape in metastatic tumors, then environmental stressors, chronic inflammation, and social adversity may be biologically embedded in cancer in ways that precision medicine alone cannot undo. The research team calls for laboratory studies of environmental exposures, epidemiological work on molecular subtypes by deprivation, and implementation science aimed at dismantling barriers to targeted therapy access. The team also plans structured patient interviews to understand precisely why eligible patients in high deprivation areas miss out on PI3K inhibitors. In the meantime, the study stands as a molecular argument that zip code should not determine tumor biology, treatment, or survival, and that closing the gap will require intervening on the neighborhoods themselves, not just the cancers within them.

Subject of Research: Associations between neighborhood deprivation and breast cancer tumor genomics, targeted treatment use, and survival in metastatic breast cancer patients

Article Title: Associations of neighborhood deprivation with breast cancer tumor genomics, targeted treatment use, and survival

Article References: Podany, E. L., Foffano, L., Gerratana, L., Medford, A. J., Heater, N. K., Nicolò, E., Tapiavala, S., Pontolillo, L., Putur, A., Jaber, D. A., Clifton, K., Katakam, N., Addison, S., Lipsyc-Sharf, M., Reduzzi, C., Ademuyiwa, F. O., Puglisi, F., Gradishar, W. J., Ma, C. X., … Davis, A. A. (2026). Associations of neighborhood deprivation with breast cancer tumor genomics, targeted treatment use, and survival. Breast Cancer Research and Treatment, 219(2), Article 5. https://doi.org/10.1007/s10549-026-08068-3

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08068-3

Keywords: breast cancer, neighborhood deprivation, Area Deprivation Index, TP53, circulating tumor DNA, PI3K inhibitors, health disparities, precision oncology, metastatic breast cancer, survival, social determinants of health, liquid biopsy