The study reviewed here found that African American women are 3 times more likely than white or Hispanic women to be diagnosed with triple-negative breast cancer.
Triple-negative breast cancer is:
Triple-negative breast cancers are usually more aggressive, harder to treat, and more likely to come back (recur) than cancers that are hormone-receptor-positive or HER2-positive. Triple-negative breast cancers don't usually respond to hormonal therapy medicines or the targeted therapies Herceptin (chemical name: trastuzumab) and Tykerb (chemical name: lapatinib).
Researchers looked at the medical records of 415 women of various races who had been diagnosed with breast cancer and noted certain characteristics of each cancer:
The differences in cancer characteristics weren't due to age or weight, both of which can affect hormone receptor and HER2 status. So, it's likely that genetic factors may be responsible for the higher incidence of triple-negative breast cancer in African American women.
Other research has shown that compared to women of other races, African American women are:
As this study shows, it's likely that the greater risk of triple-negative breast cancer faced by African American women partially explains why breast cancer in African American women tends to be more advanced, more aggressive and harder to treat.
If you're an African American woman, you can't change your genes. But you can make sure that any breast cancer is diagnosed at its earliest, most treatable stage. If you're older than 40 with an average risk of breast cancer, this means getting a mammogram each year. If you have higher-than-average risk, you may have a more aggressive screening plan that starts at a younger age. Between mammograms, make sure your doctor or other healthcare provider does regular breast exams. You also should consider doing regular breast self-exams. Tell your doctor right away if you find anything you're concerned about. If you need to know how to do a self-exam, ask your doctor.
To learn more, visit the Breastcancer.org Screening and Testing section.
BOSTON, March 25 (MedPage Today) -- Black women may be at increased risk for aggressive, difficult-to-treat triple-negative breast cancer, independent of their age and weight, researchers found.
Tumors that did not express estrogen or progesterone receptors or HER2 were three times more common among black women than among white women (P=0.0001), Carol L. Rosenberg, M.D., of Boston University Medical Center, and colleagues reported online in Breast Cancer Research.
The effect of race or ethnicity in the single center cohort did not vary with age and body mass index, suggesting that triple-negative disease "likely contributes to black women's unfavorable breast cancer prognosis," the researchers said.
Black women in the U.S. have an overall lower risk of developing breast cancer overall than their white peers, but their cancers are diagnosed at a higher stage, with a greater risk of recurrence and worse prognosis.
Prior studies have found a higher rate of triple-negative breast cancer in minorities including blacks.
So, to determine what factors might explain these disparities, Dr. Rosenberg's group created a database of invasive breast cancer cases seen at their tertiary "safety net" center, which serves a highly diverse population.
Among the 415 women in the database, the largest proportion -- 43% -- classified themselves as black, followed by white (36%), Hispanic (10%), and "other" (11%), which encompassed Indian and Middle Eastern women.
These women tended to be younger than the average American breast cancer patient (median age 58 versus the national average of 61), although the proportion in the premenopausal age range was similar to the national average.
Overall, 20% of the women had triple-negative tumors while 72% expressed estrogen, progesterone, or both types of receptors. Some 13% were HER2 positive.
However, triple-negative breast cancer was not evenly distributed among racial and ethnic groups. Black women had a 30% rate of these aggressive tumors compared with just 11% to 13% in the other groups.
In a multivariate regression analysis, triple-negative status was three times more likely among black than white women (95% confidence interval 1.6 to 5.4).
This association remained strong in a model that mutually adjusted for race or ethnicity, BMI, and age under-or-over-50 as a surrogate for menopausal status (P=0.0001).
Although overweight and obesity were common among black women with hormone nonresponsive tumors, BMI did not appear to be associated with triple-negative status.
The excess risk among black women was not greater for those who were obese than for those who were not obese (OR 4.3 for black versus non-black obese, P=0.0004; and OR 2.7 for black versus non-black non-obese, P=0.003). These two ORs were not significantly different from one another (P=0.41), suggesting that among black women, BMI does not appear to be associated with triple-negative status.
Likewise, age did not appear to matter in risk of triple-negative breast cancer among black women (31% of those in patients 50 and younger versus 29% of those in the over 50 group, P=0.76).
Even in the overall group, the association of triple-negative status with younger or premenopausal age typically described in other studies was weak (P=0.22).
The researchers noted that older age and higher BMI have been linked with hormone receptor positive status and better prognosis in other studies.
The contrast in findings "may be due to the unusual heterogeneity of our population, with consequent diversity of socioeconomic, lifestyle, and genetic factors," Dr. Rosenberg's group said.
This highlights the "complexity surrounding the issue of race and ethnicity in medical research, and the potential differences in how each can be defined, measured, and interpreted," they added.
They acknowledged their study's relatively small size and lack of data on clinical outcomes, individual socioeconomic status, and potential confounders, including parity and age at menarche.
For example, nulliparous women are at increased risk for breast cancer compared with parous women; the relative risk ranges from 1.2 to 1.7. Younger age at menarche is also associated with a higher risk of breast cancer.
The study was supported by the LaPann Fund and the Research Enhancement Fund. The researchers reported no conflicts of interest.
Primary source: Breast Cancer Research Source reference: Stead LA, et al "Triple-negative breast cancers are increased in black women regardless of age or body mass index" Breast Cancer Res 2009; 11: R18.
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