Cancer specialists at MedStar Washington Hospital Center are trying to find out why African American women are showing up for treatment with advanced breast cancer at rates that are almost double the national average.

Of 1,764 women who went to the hospital for breast cancer treatment from 2006 to 2011, 311 of them, or about 18 percent, had stage 3 or stage 4 breast cancers. Nationwide, 10.5 percent of all breast cancer cases are stage 3 or stage 4, according to National Cancer Institute data.

“We don’t know why we are having all these cases with advanced cancer,” said Elmer E. Huerta, director of the cancer-prevention program at the hospital.

Of the 311 with advanced breast cancer, 169, or 54 percent, were women who lived in the District, and most of them were black. And of those, 68 women, or 40 percent, were residents of Ward 5, where the hospital is located. Ward 5 is mostly in Northeast Washington and includes the neighborhoods of Brentwood, Brookland and Fort Lincoln.

Officials did not have ward breakdowns for the other cases. Ward 5 has the highest breast cancer mortality rate of the city’s eight wards, according to the D.C. Cancer Consortium, a nonprofit organization.

Locator for the District's Ward 5.

Initially, hospital researchers suspected that lack of access to health care might be one reason for the higher rates of advanced cancer; it is a reason the District has one of the country’s highest cancer mortality rates.

But to their surprise, hospital officials found that 97 percent of the Ward 5 patients with advanced breast cancer were African American women with insurance coverage.

“It is striking that women who have medical insurance are presenting late with a disease” that could have been detected earlier with screening, Huerta said.

Hospital officials don’t know why that is happening. One possible reason is fear, Huerta said. But another explanation may be that many women are confused about the importance of mammograms because of conflicting studies about their benefits and risks, he said.

One 42-year-old woman who recently began treatment for advanced breast cancer told Huerta that her doctor recommended a mammogram after she turned 40. But the woman put it off because conflicting information about screenings made her think “it was not important to do,” Huerta said.

Huerta and others cautioned that the analysis was conducted only at Washington Hospital Center and that this is the first time the hospital’s Cancer Institute has looked at cancer data in this way.

On Friday, the hospital received a $100,000 grant from the Avon Foundation to begin a community outreach program to educate women in Ward 5 about mammograms. The hospital plans to hire a breast health educator from the community to visit beauty parlors and other locations to increase awareness of screening, diagnostic and treatment services.

The District has a higher rate of breast cancer mortality than any of the states: 27.6 per 100,000 in 2008, compared with a national average of 23.5, according to the D.C. Cancer Consortium. The 2008 breast cancer death rate in Ward 5 was 40.5 per 100,000, followed closely by 39 per 100,000 in Ward 8, and 29.9 per 100,000 in Ward 7.