“Our study explored the incidence of breast cancer within the context of the Environmental Quality Index (EQI) – a county-by-county assessment of air, water, land, built environment, as well as the sociodemographic environment,” Devi said. “This type of data analysis allows for a high-level look at broader environmental factors and health outcomes.”
Devi and colleagues — including lead author Larisa M. Gearhart-Serna, who steered the research as a Ph.D. candidate at Duke – analyzed the EQI data alongside breast cancer incidence rates from the North Carolina Central Cancer Registry. The team further evaluated the different breast cancer stages – in situ and localized (early stages), regional and distant (later stages) — stratified by rural-urban status.
“This is a continuation of that work to determine whether environmental quality and an urban environment are related to the development of more advanced tumors in a community and, if so, what stages,” Gearhart-Serna said.
In counties with poor overall environmental quality compared to those with good environmental quality, total breast cancer incidence was higher by 10.82 cases per 100,000 persons. This association was most pronounced for localized breast cancer.
The researchers also found that community level effects of environmental exposures — notably in those counties with poor land quality, especially in the urban setting — were associated with 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.
Breast cancer incidence rates were also higher for later stage disease and total breast cancer among counties with higher populations of Black residents. This is relevant as global incidence of aggressive breast cancers is higher in Black women.
The analysis found that higher mammography screening rates were associated with lower regional breast cancer incidence rates, which is relevant because improved screening is thought to decrease diagnoses of later-stage disease.
“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,” Gearhart-Serna said. “This has the potential to develop measures to reduce disease incidence in vulnerable communities.”
The research is a result of a long-standing collaboration between Duke’s School of Medicine and Nicholas School of the Environment.