Duke Health’s analysis of breast cancer in North Carolina has unveiled a distinct pattern, indicating higher incidences of the disease in urban counties compared to rural ones, particularly during early stages of diagnosis. The comprehensive findings, featured in the journal Scientific Reports, present a national framework for evaluating the impact of environmental quality on breast cancer across various stages, considering the diverse origins and mechanisms of the disease.
North Carolina, with its diverse population of 10 million spread across 100 counties with varying environmental conditions, serves as an ideal model for this research. Senior author Gayathri Devi, Ph.D., a professor in Duke’s departments of Surgery and Pathology, as well as the Program Director of the Duke Consortium for Inflammatory Breast Cancer at the Duke Cancer Institute, emphasized the longstanding association between individual environmental contaminants and breast cancer.
However, there is limited understanding of how multiple exposures simultaneously influence the disease. The study aimed to fill this knowledge gap by exploring breast cancer incidence in the context of the Environmental Quality Index (EQI), which assesses air, water, land, built environment, and sociodemographic factors on a county-by-county basis.Â
Devi explained, “This type of data analysis allows for a high-level look at broader environmental factors and health outcomes.” The research team, led by Larisa M. Gearhart-Serna, a Ph.D. candidate at Duke, examined EQI data alongside breast cancer incidence rates from the North Carolina Central Cancer Registry. They specifically evaluated the different stages of breast cancer—ranging from in situ and localized (early stages) to regional and distant (later stages)—while considering rural-urban distinctions.Â
In counties with poor overall environmental quality, compared to those with good quality, the total breast cancer incidence was higher by 10.82 cases per 100,000 persons. This association was most notable for localized breast cancer. The study also highlighted that community-level effects of environmental exposures, especially in urban settings with poor land quality, were linked to higher rates of total breast cancer incidence. The land EQI includes exposures from sources such as pesticides and toxic releases from industrial, agricultural, and animal facilities.Â
Furthermore, the analysis indicated higher breast cancer incidence rates, particularly for later-stage disease and total breast cancer, in counties with higher populations of Black residents. This observation is particularly relevant as global incidence rates of aggressive breast cancers tend to be higher in Black women. Additionally, the research found that higher mammography screening rates were associated with lower regional breast cancer incidence rates. Improved screening is thought to decrease diagnoses of later-stage disease.Â
Gearhart-Serna emphasized the significance of the findings, stating, “Our analyses indicate significant associations between environmental quality and breast cancer incidence, which differ by breast cancer stage and urbanicity, identifying a critical need to assess cumulative environmental exposures in the context of cancer stage.” The research underscores the importance of considering environmental factors in breast cancer incidence and highlights the potential for developing measures to reduce disease incidence in vulnerable communities.Â
This groundbreaking research is a result of a longstanding collaboration between Duke’s School of Medicine and Nicholas School of the Environment. The study’s co-authors include Brittany A. Mills, Hillary Hsu, Oluwadamilola M. Fayanju, and Kate Hoffman. The findings provide valuable insights into the complex interplay between environmental factors, urban settings, and breast cancer, paving the way for more targeted interventions and strategies to reduce the burden of the disease in affected communities.Â
Journal Reference Â
Larisa M. Gearhart-Serna et al, Cumulative environmental quality is associated with breast cancer incidence differentially by summary stage and urbanicity, Scientific Reports (2023). DOI: 10.1038/s41598-023-45693-0Â
