Environmental Quality as a Whole Could Impact Cancer Incidence

Exposure to harmful environmental factors was linked with cancer incidence across the United States, according to the results of a study published in Cancer.

Jyotsna S. Jagai, MS, MPH, PhD, of the division of environmental and occupational health sciences at the University of Illinois at Chicago, and colleagues investigated the overall environmental quality across multiple domains including air, water, and land quality; sociodemographic environment; and built environment. They linked the Environmental Quality Index (EQI), a county-level measure of cumulative environmental exposures, with cancer incidence rates from the Surveillance, Epidemiology, and End Results Program state cancer profiles.

“Our county-level analyses demonstrated positive association between cumulative environmental quality and cancer incidence for all rural/urban strata,” the researchers wrote. “This study demonstrates that focusing on single environmental exposures in cancer development, though necessary to understand specific mechanisms, may not address the broader environmental context in which cancers develop and that future research should address the impact of cumulative environmental exposures.”

Of the counties assessed for the analysis, 34% were metropolitan urbanized, 10% were non–metropolitan urbanized, 34% were less urbanized, and 21% were thinly populated, which the researchers said mirrors the distribution of all US counties.

The mean annual county-level age-adjusted incidence rate for all types of cancer was 451 cases per 100,000 people. When the highest quintile (poorest environmental quality) was compared with the lowest quintile (best quality) for overall EQI, the all-site county-level cancer incidence rate was positively associated with poor environmental quality overall (incident rate difference [IRD], 38.55; 95% CI, 29.57–47.53). This means that on average there were 39 more cases of cancer per 100,000 people in counties with poor environmental quality. This association was also found for both male (IRD, 32.60; 95% CI, 16.28–48.91) and female individuals (IRD, 30.34; 95% CI, 20.47–40.21).

The researchers also looked at the top three site-specific cancers. Data showed that both prostate cancer and breast cancer had positive associations with environmental quality when comparing the poorest environmental quality areas with the best quality areas overall (prostate: IRD, 10.17; 95% CI, 0.84–19.50 and breast: IRD, 7.29; 95% CI, 3.05–11.54).

In an editorial that accompanied the article, Scarlett Lin Gomez, PhD, Salma Shariff-Marco, PhD, Iona Cheng, PhD, MPH, and Peggy Reynolds, PhD, MPH, of the Cancer Prevention Institute of California, noted that the study is an excellent example of the value of geospatial data in cancer control research.

“These data are fundamental to documenting which communities are most vulnerable in terms of high cancer rates, and which geographically determined factors may be driving community-level disparities,” they wrote.

They also stressed that recent legislative proposals that seek to suppress the federal collection of geospatial data, such as the Local Zoning Decisions Protection Act of 2017, which was introduced in January and seeks to prohibit the use of federal funds for the collection of geospatial data on racial and community disparities, could severely and negatively impact this type of research and policy efforts guided by these types of data.