Genes May Hold Key to Breast Cancer in Blacks

Genetics may be why U.S. black women tend to get more advanced breast cancer.

Even though black women get breast cancer less often, when they do, it’s often more advanced than in white women.

Now, researchers have found similarities in breast cancer between African women and U.S. black women. This, they say, points to a possible genetic cause for more advanced breast cancers among black American women (search).

The researchers noticed several parallels between breast cancer patients in Africa and black women with breast cancer in the U.S.

Both groups tend to get breast cancer at younger ages than white women. They are also often diagnosed with more advanced breast cancers. Black women with breast cancer in the U.S. and Africa also die more often from the disease than white women.

Millions of Africans were removed from their homes and enslaved in the U.S. centuries ago. Most came from sub-Saharan Africa. Could that long-ago connection also include a breast cancer pattern still seen today?

Genes and Ancestry

The University of Michigan’s Alero Fregene, MD, and Lisa Newman, MD, MPH, explored the topic. They searched for African breast cancer studies reported in English from 1988 to 2004.

All studies focused on women from sub-Saharan Africa because of their shared ancestry with black U.S. women. This excludes northern nations including Morocco, Tunisia, Algeria, and Egypt. Each study had to have at least 50 women.

Three key findings emerged.

First, black women in the U.S. and Africa had several things in common. Second, breast cancer is poised to rise in Africa, as more Africans adopt Western lifestyles. Last but not least, breast cancer education, diagnosis, treatment, and research are severely lacking in many parts of Africa.

Younger Age at Diagnosis

Breast cancer frequency was “quite low” in Western Africa, striking about 20 out of 100,000 women, says the study. In the West, the rate is 90 out of 100,000 women, says a news release.

In Africa, most women with breast cancer are diagnosed between ages 35-45 years. That’s about 10-15 years earlier than the peak for countries in the West, says the study.

In America, more black women than whites are diagnosed with breast cancer before age 45. On average, black women are diagnosed at 57, compared to 63 for white women, says the study.

More Advanced Breast Cancer, More Deaths

In Africa, fewer women are diagnosed with breast cancer, but a disproportionate number of them die from it, says the study.

The same is true for black women in the U.S. “African-American women have a lower lifetime risk of being diagnosed with breast cancer, accounting for approximately 8 percent of all estimated new cases in the USA,” write the researchers. “In contrast, they account for approximately 13 percent of all breast cancer deaths.”

African and black American women also tend to have more advanced breast cancers that aren’t estrogen (search) sensitive. Breast cancer in white women often grows in response to the hormone estrogen.

Those similarities may indicate common genetic features shared by black women on both continents, the study suggests.

A World Away

That’s a provocative possibility, but it’s not a proven fact, says the study. Much more work needs to be done on breast cancer in Africa, write the researchers.

Genetic and population studies are needed. Those could reveal more about gene patterns and lifestyle factors. For instance, African women tend to start menstruation later, have more babies at younger ages, and breast feed longer -- all of which are associated with less breast cancer.

But that’s just the tip of the iceberg. There is an immediate need to help patients and to get the word out about breast cancer.

Breast cancer is likely to rise as more Africans take on Western lifestyles. Researchers have seen the same thing happen in Asian populations, where breast cancer becomes more common in second- and third-generations who’ve moved to America.

In Africa, funds and equipment are often scarce. There are only two screening mammography units in the entire country of Uganda, says the study. With few resources, whatever care women may get could come too late.

Breast cancer education is also needed. The University of Michigan researchers noted that in a Nigerian study of 204 nurses, 31 percent were unfamiliar with breast cancer risk assessment and most didn’t think they were personally at risk. In another Nigerian study, 85 percent of 200 schoolteachers said they knew that breast cancer was a serious disease, but only 53 percent knew that a breast lump was a significant symptom.

The study appears in the journal Cancer’s April 15 edition.

By Miranda Hitti, reviewed by Michael W. Smith, MD

SOURCES: Fregene, A., Cancer, April 15, 2005; vol 103. News release, John Wiley & Sons, Inc.