Oct. 28, 2012 -- African-American women may be more likely to die of breast cancer than women of other races, especially in the first few years after the diagnosis, according to new research.
As to why, there are no clear answers yet, but the emphasis on vigilant care is clear for African-American women.
"Black women were almost 50% more likely to die compared to white women within the first three years since breast cancer was diagnosed," says researcher Erica Warner, ScD, MPH, a postdoctoral research fellow at the Harvard School of Public Health.
That higher risk of death was driven by African-American women who had estrogen receptor-positive tumors, she found. These tumors are usually more treatable than other types.
Asian women, in comparison to whites or African-Americans, had a lower risk of dying from breast cancer, she found.
Warner presented the study today at the American Association for Cancer Research conference on cancer health disparities in San Diego.
About 227,000 new cases of invasive breast cancer will be diagnosed this year, the American Cancer Society predicts, with nearly 40,000 deaths.
Women & Breast Cancer: Ongoing Research
The overall results are not surprising, Warner says. "Other people have shown differences in survival, black compared to white," she says.
"While black women are less likely to get diagnosed with breast cancer than white women, they are more likely to die if diagnosed," she says, citing previous research.
In her study, she says, she looked more closely than some other researchers have at tumor subtypes. She found the death risk more striking among African-American women with the ER-positive tumors.
In all, Warner evaluated more than 19,000 women who got care at National Comprehensive Cancer Network centers from January 2000 though December 2007. These centers are an alliance of 21 leading cancer centers.
More than 16,000 of the women were white. Another 1,500 were African-American, more than 600 were Asian, and about 1,300 were Hispanic. All the women were diagnosed with stage I to III breast cancer.
Warner followed the women for about seven years (half were followed longer, half long).
She took into account such factors as age, tumor features, stage when diagnosed, and treatments.
Asians were 40% less likely than whites to die of breast cancer during the follow-up.
African-Americans were nearly 50% more likely than whites to die of breast cancer during the follow-up.
That first three years after diagnosis, Warner says, were especially risky.
When she took into account age and tumor features, she found no differences between African-American and white women for certain tumors, including estrogen receptor-negative tumors. These are typically more aggressive than others.
Warner can't fully explain the findings.
"We've put everything we can think of in our model," she says, as a way to explain survival differences. "We still find persistent differences in survival."
"We thought it might have something to do with treatment differences, but we accounted for disparities and the differences persisted," Warner says.
However, she says, there could still be some treatment differences not fully accounted for that could help explain the higher death risk.
"On average, black women in our study were diagnosed at a later stage," she says.
Body mass index at diagnosis plays a role in survival, she says. Higher BMIs are linked with lower survival. "We see differences starting at [a BMI of] 25," she says. A BMI of 25 is termed overweight.
The biggest survival differences, she says, are seen at BMIs of 30 and higher, termed obese, Warner says.
African-American Women & Breast Cancer: Perspective
"Their findings are certainly consistent with previous work examining racial disparities in breast cancer mortality," says Swann Arp Adams, PhD, assistant professor and associate director of the Cancer Prevention and Control Program at the University of South Carolina, Columbia.
Adams' study on racial disparities was published in the journal Cancer earlier this year. She, too, found that African-American women had lower survival after breast cancer than other ethnicities.
However, Adams says, it's not all gloom and doom.
Many public health programs, she says, are trying to improve the outlook. "Here in South Carolina, the Best Chance Network, which is a part of the National Breast and Cervical Cancer Early Detection Program, provides free mammograms and Pap smears to income-eligible women."
The program, she says, has been shown to help women of all races get a diagnosis earlier.
To improve their odds, Warner says, women diagnosed with breast cancer should seek a second opinion and find the best care they can.
Women in rural or underserved areas should consider asking for a referral to a larger center, Warner says.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.