Studies Reveal Why Breast Cancer Hits Black Women Harder
Biology and genetics appear to be key factors, researchers say
THURSDAY, Nov. 29, 2007 (HealthDay News) -- Biology and genetics -- over and above socio-economic factors -- appear to influence how black women fare after being diagnosed with breast cancer, U.S. researchers are reporting.
One new study found discrepancies in survival rates between black breast cancer patients and their white counterparts, indicating that cancer screening guidelines may need to be revised.
A second study, conducted by researchers at the U.S. National Cancer Institute, found clear genetic differences in the breast cancer tumors of black women as compared with white women. This could influence how the disease progresses and how it responds to therapy, the study authors said.
These findings are in line with previous research.
"Those of us who treat breast cancer every day are well aware that African-Americans just have a more aggressive breast cancer. Stage for stage, they do worse," said Dr. Brenda J. Sickle-Santanello, senior medical director of Breast Health Services at Ohio Health and medical director of oncology at Grant Medical Center in Columbus.
"African-Americans are underrepresented in research studies. I hope this will heighten awareness to people who do the research to try and target African-American populations," she added.
The new studies and other research documenting racial disparities in breast cancer are being presented this week at the American Association for Cancer Research conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, in Atlanta.
Differences in breast cancer survival rates between black and white women are often attributed to non-biological reasons, such as access to health care and various socio-economic factors. While these factors are no doubt important, a growing body of research also points to biological explanations that may account for the differences.
Black women tend to have more aggressive, estrogen-receptor-negative breast tumors that don't respond to newer hormonal therapies, experts say. They also tend to have a higher rate of lymph node involvement.
The first study, by researchers at the University of Chicago, looked at 1,246 women with stage I or stage II invasive breast cancer treated with lumpectomy and radiation.
Eight years after treatment, 84.9 percent of white women were alive and free of disease, compared to 78.1 percent of black women. Similarly, 31.6 percent of black women experienced a relapse at this point in time, versus 14.9 percent of all other women.
Current screening mammography guidelines might need to be revised to benefit black women, the authors reported.
"Maybe we should be more aggressive in general and systemic therapy, even in screening," Sickle-Santanello agreed.
The second study identified differences in the gene profiles of tumors, including those involved with angiogenesis (blood vessel development) and how tumor cells interact with the immune system.
Many of the same genes are active in inflammatory diseases such as chronic colitis. Previous studies have shown a link between these inflammatory conditions and cancer.
Finally, a third study looked at whether various groups of women, including black women, were undergoing auxiliary lymph node dissection, which can indicate whether the breast cancer has spread to other parts of the body.
After plying data on close to 200,000 women, the investigators found that uninsured women were 24 percent less likely to have their lymph nodes assessed, compared to women with private insurance.
Women who lived in areas with low education levels were 13 percent less likely than those from high education areas to undergo the procedure, and black patients were 10 percent less likely than white patients to have their lymph nodes accurately assessed.
Age was also a factor, with women 73 or older three times less likely to get the procedure, compared with women aged 51 or younger. Lymph node dissection is considered optional for elderly women but, even so, the researchers were surprised by the size of the discrepancy.
Overall, 11 percent of patients in the database did not undergo the procedure.
"In general, there shouldn't be a non-clinical reason that influences whether or not patients receive this important diagnostic procedure," said Dr. Michael Halpern, study lead author and strategic director of health services research at the American Cancer Society. "We don't have any idea on exactly why this happens. Our guess is that there are a number of barriers related to communication between patients and physicians."
The American Cancer Society has more on race, ethnicity and breast cancer.