BLACK PATIENTS AND TRIPLE NEGATIVE BREAST CANCER

July 29, 2010 — A link between estrogen receptor–negative (ER-negative) and triple-negative breast cancer and African ancestry has been reported again in a new study published online July 22 in Cancer.

Researchers from the University of Michigan Comprehensive Cancer Center in Ann Arbor report that in their cohort, 82% of African women and 26% of American women of African ancestry had triple-negative disease. This was compared with 16% of white American patients with breast cancer.

As previously reported by Medscape Medical News, black women tend to be diagnosed at a younger age, present with a more advanced stage of disease at diagnosis, and have a higher risk for recurrence. They are also more likely to present with the triple-negative phenotype (negative for ER, progesterone receptor [PR], and human epidermal growth factor receptor 2 [HER2]), and are more likely to be ER-negative, which makes these women ineligible for hormone therapy.

Although the overall incidence of breast cancer among American black women is lower than in white women, breast cancer–related mortality is higher. However, even though multiple factors play a role in this disparity, studies have also shown that there may be biologic differences involved.

"While there are socioeconomic, cultural beliefs, and lifestyle factors involved, we believe that molecular differences also contribute to the more aggressive clinical features of breast tumors seen in these women," said Lori Field, PhD, the lead author of a study on genetic differences between black and white patients with breast cancer that was presented at the American Association for Cancer Research 2008 Annual Meeting. Dr. Field was with the Windber Research Institute, in Pennsylvania, when she presented her data.

Another recent study reported that triple-negative disease is 3-fold more common in black women compared with other races, regardless of age or body mass index. (Breast Cancer Res. 2009;11:R18).

Highest Prevalence of ER-Negative and Triple-Negative Disease

"A primary message of this work is that initiation of mammography screening at age 40 is particularly important for African-American women because of their increased risk for early-onset disease and for disease that is biologically more aggressive," said lead author Lisa A. Newman, MD, MPH, director of the Breast Care Center at the University of Michigan.

"Early detection of triple-negative breast tumors is extremely important," she told Medscape Medical News. "I personally advocate for mammography screening beginning at age 40 for white American women as well, in accord with American Cancer Society and American College of Surgeons recommendations."

In the latest study, Dr. Newman and colleagues compared disease patterns and selected clinicopathologic features among white and black American patients with breast cancer and African women with breast cancer who were treated at the Komfo Anokye Teaching Hospital in Kumasi, Ghana.

The study cohort included 1008 white American women, 581 black American women, and 75 Ghanaians, all of whom were diagnosed with invasive breast cancer. The mean age at the time of the diagnosis for Ghanaian women was 48 years, which was considerably lower than the median 60.7 years for black American women and 62.4 years for white American women (P = .0019).

The authors noted that the percentage of grade 3 lesions was also higher for the Ghanaian patients, as was the tumor size. Approximately three quarters (76%) of the Ghanaian patients were also diagnosed with ER-negative tumors compared with 36% for black American women and 22% for white American women. Ghanaian women also had the highest prevalence of triple-negative breast cancers observed in this group.

Within this cohort, 28 white American women (2.8%), 46 black American women (7.9%), and 57 Ghanaian women (76%) were diagnosed with poorly differentiated and stage III/IV breast cancer. An absence of expression of ERs was observed in 77.2% (n = 44) of Ghanaian women, 67.4% (n = 31) of black American women, and 50.0% (n = 14) of white American women (P = .043)

The authors also stratified the 2 cohorts of American women according to their menopausal status and then compared this status with the frequency of triple-negative breast cancers. Among premenopausal patients, black women had a higher prevalence of triple-negative breast cancer compared with white women, at 32.3% vs 25.2%. Both of these percentages were significantly lower than the rate observed among Ghanaian patients (82%), of whom the majority was younger than the commonly used menopausal surrogate cutpoint of 50 years. However, the authors point out that regardless of age, non-triple-negative tumors were rare among Ghanaian patients.

"Our study documented provocative patterns of increasing frequency for early onset/younger age at diagnosis, ER-negative/PR-negative, and triple-negative breast cancers in association with presumed increasing extent of African ancestry," the authors write. Further study of the breast cancer burden in African women could lead to identifying tumors or germline markers associated with high-risk disease, they suggest.

"Research programs that promote inclusion of African-American women onto clinical trials are extremely exciting," said Dr. Newman, pointing out that most National Cancer Institute–funded clinical trials' cooperative groups have Special Populations/Diversity Committees that specifically focus on enhanced accrual of diverse patient populations.

"I am currently working with my colleagues at the University of Michigan to develop clinical trials for breast cancer that we hope to activate in Ghana," she added.

Coauthor Celina G. Kleer, MD, was supported by a National Institutes of Health grant.

Cancer. Published online July 22, 2010.