Using government data on breast cancer screening and diagnoses, researchers found that rates of mammography screening improved for U.S. women of all races during the 1990s. By the end of the decade, African American and Hispanic women were even more likely than white women to have been screened in the past year.

Despite this, however, African Americans were less likely than whites or Hispanics to have their cancer diagnosed at an early stage, when it was still confined to the breast tissue.

Though the study could not discern the reasons for the racial gap, there are a number of possible explanations, the researchers note in the study, published in the current issue of the American Journal of Public Health.

One is that while African American women may get screened, they may also be less likely to have a timely follow-up visit when their mammogram results are abnormal, according to lead study author Dr. Franco Sassi.

"African-American women do appear to receive less, or less adequate, follow-up of screening test results," Sassi, a researcher at the London School of Economics and Political Science in the U.K., told Reuters Health.

This may be partly related to a lack of health insurance, he said, but that's unlikely to be the main reason, because uninsured women are less likely to be screened in the first place.

Sassi and his colleagues based their findings on data from cancer registries in five U.S. states for the years 1990 through 1998, as well as federal statistics on mammography screening for the same time period.

Over time, the researchers found, screening rates ticked upward for all three racial groups, particularly Hispanic women. The rate of early diagnosis also climbed.

But the benefit was less pronounced among African American women, the study found. While mammography screening doubled the chances of early diagnosis among white and Hispanic women, it raised those odds by only 70 percent among African American women.

The reasons, according to Sassi's team, are likely to involve a "complex interplay" of factors.

It's possible, they note, that some of the highest-risk African American women are not getting screened. Research has shown, for example, that African American women with a family history of breast or ovarian cancer are less likely than their white counterparts to be tested for the genes linked to familial breast cancer.

African American women are also more likely than white or Hispanic women to be obese, which has been linked to later breast cancer diagnosis, even when women get screened.

Sassi noted that government programs to help low-income women get mammograms have "done a lot" to increase screening rates among minority women. But funds for follow-up diagnosis and treatment have been limited, and are still "less than ideal," he said.

Policy makers, according to Sassi, may need to focus not only on improving breast cancer screening, but also on ensuring that mammography leads to earlier diagnosis.

SOURCE: American Journal of Public Health, December 2006.

Copyright © 2006 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.