NEW YORK -- Pre-menopausal black women with breast cancer are twice as likely to have a more aggressive tumor than non-black women of any age or post-menopausal black women, scientists report. Doctors hope the finding will encourage more adult black women to undergo routine mammography.
"This is powerful information," said Dr. Lisa A. Carey, medical director of the University of North Carolina's Lineberger Comprehensive Cancer Center and lead author of the study published today in the Journal of the American Medical Association. "Young black women [under 50] are at greater risk for this particular subtype of cancer. We now know that breast cancer is not just one disease, but tumors are biologically distinct with different prognoses."
Basal-like breast cancer is one of the most aggressive tumors. Doctors call it a "triple negative" because the three protein markers now targeted with the latest cancer medicines don't show up in these tumors. So patients must rely, not on the latest targeted therapies, but on standard forms of chemotherapy, which come with many more side effects.
It has long been observed that black women have a poorer prognosis than non-black women once a diagnosis has been made. It had been thought that disparities in access to medical care was the root cause. "Part of the reason may be the nature of the cancer itself," Carey said.
"It's a well-done study," said Dr. Larry Norton, medical director of Memorial Sloan-Kettering's Evelyn H. Lauder Breast Center in New York. "The more clues we have ... the better we can diagnose, treat and prevent these breast cancers."
"It could be that lots of genes are involved and it's hard to trace," Norton said of this subtype of cancer. There is preliminary evidence that these tumors are the most common ones in Africa, as well.
Carey and her colleagues used protein tests on almost 500 women from the Carolina Breast Cancer Study. They used this extensive study to look for characteristics of certain tumors and their frequency in different populations. They found the basal-like tumors were in 39 percent of pre-menopausal black women, compared with about 15 percent in post-menopausal black women and in non-black women.
The doctors also found that these younger black women were less likely to be diagnosed with luminal A tumors, a less aggressive cancer. The luminal tumors are responsive to estrogen-based therapies.
"Once you know what genes are turned on, we can begin to develop target treatments," Carey said.
Age-adjusted mortality in the United States from breast cancer in white women is 28.3 deaths per 100,000 compared with 36.4 deaths in black women, according to the report. The disparity is more pronounced among women younger than 50.
Margaret Rosenzweig of the University of Pittsburgh School of Nursing, who was not involved in the UNC study, said black women may be less likely than white women to follow through on their treatment.
Rosenzweig and her colleagues, in a small study presented in Atlanta last week at the annual meeting of the American Society of Clinical Oncology, showed that poor black women with breast cancer had more difficulty understanding and accepting their treatment than other racial and income groups.
Jamie Talan writes for Newsday. The Associated Press contributed to this article.