TUESDAY, Oct. 1, 2013 (HealthDay News) -- White women 40 and older have traditionally had the highest rates of breast cancer in the United States, but rising rates among blacks have narrowed the gap in recent years, according to a new American Cancer Society report.
"This convergence of rates is being driven by steady rates among white women and a slow increase in recent years among African-American women," said report co-author Carol DeSantis, an epidemiologist in the society's Surveillance and Health Services Research Group.
From 2006 through 2010, breast cancer rates increased 0.2 percent among black women but remained stable among whites, researchers found. White women still have more cases of breast cancer, however, with about 127 cases per 100,000 compared with 118 cases per 100,000 black women.
But deaths from breast cancer are more common among blacks, according to the report published Oct. 1 in CA: A Cancer Journal for Clinicians.
The gap is closing most among women aged 50 to 59 years old, and the reasons why aren't clear, the researchers say.
Another expert voiced concern.
"Even with all the attention and awareness raised around breast cancer, the incidence of the disease holds steady," said Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City.
"Although the incidence haven't declined, we have made strides in the effort to improve the survival rate," she noted. "Death rates have declined by 34 percent since 1990. However, not all ethnic groups are enjoying this improved survival."
The death rate during the study period was 30.8 per 100,000 among black women compared to 22.7 per 100,000 among whites, the reports says.
Blacks have a worse prognosis stage for stage, and the incidence of breast cancer in this group in increasing, Bernik said.
"The reasons for this increase among African-American women are unclear, but may be linked to socioeconomic status and barriers to treatment," she said.
Bernik added that improvement in the survival rate is encouraging, but said more work needs to be done to prevent the disease from starting in the first place.
Study author DeSantis said the most important thing a woman can do is get screened regularly. "In addition, lifestyle plays an important role," she said. "Not gaining weight, regular physical activity and only drinking moderately can help reduce the risk of breast cancer."
A majority of women are being screened, but work is needed to get even more to have regular mammograms, the experts said.
In 2010, 67 percent of women 40 and older had a mammogram in the past two years. The percent of women getting regular mammograms, however, peaked in 2000, went down slightly and has remained about the same since 2005, they said.
On the plus side, deaths from breast cancer have dropped 34 percent since 1990 among all women, except for American Indians/Alaska Native women, they found.
Yet there is still a racial disparity with black women having the worst survival rate of any group, the researchers report.
One reason for their poorer survival rate may be that blacks are being diagnosed when the cancer has already spread. This could reflect differences in the quality of screening and delayed follow-up for abnormal findings, according to the report.
Between 2006 and 2010, rates increased for the most common type of breast cancer, called estrogen receptor-positive breast cancer, among young white women, Hispanic women in their 60s, and all but the oldest black women, the researchers found.
This might be the result of more obesity and women having fewer children or not having children, DeSantis said. "These [factors] are associated with increased risk of estrogen receptor-positive breast cancers," she said.
The "good news, if one can say that," she said, is "estrogen receptor-positive breast cancers tend to be less aggressive and respond better to treatment."
The rates for estrogen receptor-negative breast cancers, however, dropped among most age and racial/ethnic groups, the researchers note. These are more aggressive and harder to treat, DeSantis said.
White women have the highest rates of estrogen receptor-positive breast cancer, and black women have the highest rates of estrogen receptor-negative breast cancer, which may be due to racial differences in risk factors, the researchers speculate.
This year, more than 232,300 new cases of invasive breast cancer and more than 39,600 breast cancer deaths are expected among U.S. women. About eight in 10 women diagnosed with breast cancer, and nearly nine in 10 women who die from breast cancer, are 50 or older, the researchers note.
For more information on breast cancer, visit the American Cancer Society.