A team of scientists assembled by the North American Association of Central Cancer Registries pulled data on 161,619 patients from cancer registries in 10 states and cross-referenced the numbers against census data.
"In all these states we looked at every woman ever diagnosed with late-stage breast cancer [age 40 and older] between 2004 and 2006," Henry said. The team's findings appear in the current issue of the journal Health & Place.
Insurance, or the lack of it, proved to be the most powerful predictor of late-stage cancer. Being uninsured raises a woman's risk of late diagnosis by 80 percent, the study showed.
Living in a neighborhood where 20 percent or more of residents live at or below the federal poverty level increased a woman's risk of late diagnosis by 30 percent.
Geographic disparities, however, surfaced in only one state with large, rural communities Iowa.
"It looks like the market has done a pretty good job at conveniently placing these screening centers," Henry said.
While the study did not include data from Utah, Henry is working with state health officials to replicate it using numbers from Utah's cancer registry. He hopes that analysis sheds light on Utah's notoriously low mammogram rates.
Co-author Recinda Sherman, an epidemiologist at the University of Miami Miller Medical School, hopes the study informs public-health-policy solutions targeting women at highest risk.
Early detection, primarily mammograms, is credited with improving breast-cancer survival rates.
Henry said President Barack Obama's signature health reform law will help by reducing the nation's uninsured rate, but it's not going to erase all burdens faced by people in poverty.
"My own thinking is some preventive care needs to center around the workplace," such as mobile screening centers and employers offering flex time for workers to get screened, he said. "Some employers don't offer sick time, and most screening centers are only open from 9 to 5 when people are at work."
In 2010, 67 percent of Utah women ages 40 and older had undergone a mammogram within the past two years the second-lowest rate in the nation. The national rate was 75 percent.