Young, Black Women at Higher Risk of Aggressive Breast Cancer

They next compared outcomes for women with triple-negative disease against those of more than 44,700 patients with breast cancers that carried the hormonal markers.

Triple-negative patients were significantly younger at the time of their diagnosis than were other breast cancer patients, the researchers found. Whereas about 63 percent of triple-negative cases were uncovered before the age of 60, less than half of other breast cancers were diagnosed in women under 60.

Women 40 years of age or under were over one-and-a-half times more likely to have triple negative breast cancer than were patients between the ages of 60 and 69, the team found.

Race was also a major risk factor. While nearly 25 percent of the black patients had triple-negative malignancies, only about 11 percent of whites, 12 percent of Asians, and 17 percent of Hispanics were similarly diagnosed.

In terms of income, richer patients were less likely to be triple-negative than poorer breast cancer patients, although the very poorest did not appear to have a significantly greater risk, the team says.

Triple-negative patients were also more likely to be diagnosed with larger tumors and at a more advanced stage of disease, the study found.

As suspected, survival was worse for triple-negative patients than for other patients. Three out of four (77 percent) of patients with triple-negative cancers survived five years post-diagnosis compared with 93 percent of other breast cancer patients.

Non-Hispanic black patients with triple-negative disease fared worst of all, having just a 14 percent five-year survival rate. By comparison, patients with other forms of late stage disease had five-year survival rates 36 and 49 percent.

Why such disparities? Caggiano's team say biological differences probably play a big role. But they also suggested that other factors, such as lack of health-care access and resulting differences in treatment could pay a role in the higher incidence of triple-negative cases among non-white patients and the poor.

"What's important to note is that breast cancer is not a single disease and even young women can get it," said Caggiano. "Why African-American and Hispanic women get this very aggressive form more often we really don't know. It may be due to genetics, socioeconomic status, or in part due to barriers to treatment. It's probably an interaction of all of them. It's clearly an area for further research."

Emily White, a researcher with the Fred Hutchinson Cancer Center in Seattle, said that "studies like this are worthwhile, and help us understand risk factors more clearly. But it's also an issue of debate whether estrogen and progesterone receptors and HER2 are fundamental [unchanging] characteristics of a tumor, or whether their status actually changes and they lose their ability to respond over time."

The notion of cancer cell change could help explain the socioeconomic disparities uncovered in this study, she said.

"If you say some tumors are simply destined to be negative from the start then you have to point to some genetic predisposition to explain it," said White, who is also professor of epidemiology at the University of Washington. "But, if you think tumors can change with time then it could be that certain socioeconomic groups get diagnosed with a more aggressive type of cancer simply because of diagnosis delays, due to health-care barriers. Whether or not this is so is not yet really understood."

More information

For more on triple-negative breast cancer, head to Breastcancer.org.

SOURCES: Vincent Caggiano, M.D., research medical director, Sutter Cancer Center, Cancer Surveillance Program, and Sutter Institute for Medical Research, Sacramento, Calif.; Emily White, Ph.D., researcher, Fred Hutchinson Cancer Center, and professor, epidemiology, University of Washington, Seattle; May 1, 2007,Cancer