Where people live in the United States may be decisive in determining whether or not they survive a cancer, new research suggests.

For example, mortality rates among women with breast cancer were much higher  in three counties in Mississippi, and two in Louisiana, in 2014 than for women residing in three counties in Colorado. The study,  “Trends and patterns of disparities in cancer mortality among US counties, 1980-2014,” was recently published in JAMA.

The study examined mortality rates for 29 types of cancer — including lung, breast and prostate cancer — in some 3,000 U.S. counties and cities between 1980 and 2014.

Overall, it reported a 20 percent decline in national mortality rates in all cancers combined, but an increase in death rates in 160 counties over those same years. These findings, the researchers said, raised questions about access to care, and cancer prevention and treatment efforts.

“Such significant disparities among US counties is unacceptable,” Ali Mokdad, MD, the study’s lead author a professor of Global Health at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, in Seattle, said in a press release. “Every person should have access to early screenings for cancer, as well as adequate treatment.”

Breast cancer mortality rates, like that of cancer overall, have decrease since 1980, but clusters of high rates were found in certain counties along the Mississippi River. The lowest rates were observed in parts of the West, Midwest and Northeast.

These five counties with the highest breast cancer mortality rates among women in 2014 were:

1. Madison County, Mississippi (52 deaths per 100,000 people)
2. Holmes County, Mississippi (47 deaths per 100,000 people)
3. Madison Parish, Louisiana (47 deaths per 100,000 people)
4. Coahoma County, Mississippi (46 deaths per 100,000 people)
5. East Carroll Parish, Louisiana (43 deaths per 100,000 people)

While the five with the lowest mortality rates for these patients were:

1. Summit County, Colorado (11 deaths per 100,000 people)
2. Pitkin County, Colorado (13 deaths per 100,000 people)
3. Eagle County, Colorado (13 deaths per 100,000 people)
4. Aleutians East Borough, Aleutians West Census Area, Alaska (15 deaths per 100,000 people)
5. Presidio County, Texas (15 deaths per 100,000 people)

Lung cancer deaths were found to be highest in  Union County, Florida (231 deaths per 100,000 people) and lowest in Summit County, Colorado (11 per 100,000) in 2014, according to the study.

“As the US enters a new debate about access to health care, these findings on the wide differences in cancer mortality should inform the discussion,” said Laura Dwyer-Lindgren, a study co-author. “What’s causing cancer to be so much more fatal in one part of the country than in other parts demands further investigation.”

The researchers suggest that smoking, diet, obesity, and others factors, combined with poor prevention programs, may increase cancer incidence in specific geographic areas. A failure to detect cancers early or a lack of specialized treatment may also play a role.

“For cancers with high survival rates, such as testicular cancer and Hodgkin lymphoma, wide differences in mortality rates in the US should raise a red flag,” said Christina Fitzmaurice, an assistant professor at IHME. “Clusters of counties with increasing death rates from these cancers need to be examined and questions raised regarding access to primary care for early detection and specialized cancer treatment services.”

Resources of possible interest on this topic include an interactive U.S. Health Map and the U.S. county profiles.