Breast Cancer :: Familial breast cancer history increases risk in African American Women, Black Women

Having a mother or sister with breast cancer significantly increases the risk for young African American women to develop breast cancer, according to the analysis of questionnaires answered by approximately 59,000 African American women enrolled in the Black Women’s Health Study.

Beginning in 1995, questionnaires were given every two years to women ? none of whom knowingly had cancer ? asking about demographics, reproductive and health history, family history of breast cancer and other factors.

According to principal investigator Julie Palmer, ScD, professor of epidemiology at Boston University, few studies have examined the relationship of family history to breast cancer risk in African American women, and none have done so prospectively.

“We wanted to see if we would confirm what had been shown in white women ? that having a mother or sister with breast cancer would increase a woman’s risk of developing breast cancer,” Palmer said.

Analyzing 10 years’ worth of follow-up questionnaires found there were 1,050 cases of breast cancer among those who completed questionnaires on family history. The team, found that the incidence rate-ratio for such women was 1.77, meaning that overall, African American women who had a first degree relative ? either a mother or a sister ? with breast cancer had 1.77 times the risk of getting breast cancer compared to another woman of the same age who didn’t have a family member with breast cancer. Having a family history of breast cancer was a stronger risk factor in women under 35, among whom the relative risk was 2.67.

Palmer said that as the study group ages and the number of women with cancer increases, the team can begin to examine other factors in cancer risk and development. “We’d expect that relative risk of 1.77 to go up quite a bit for women who have two first-degree relatives,” she said. In fact, the researchers found that the overall relative risk for breast cancer was 2.58 for having two or more first-degree relatives with breast cancer, but the figure was based on few women.

The researchers plan to examine whether having a family member with other cancers is related to heightened breast cancer risk. Palmer noted that ovarian cancer might be one such cancer because “there are some shared genes,” referring to the tumor suppressor gene BRCA1, which when damaged can increase a woman’s risk of both breast and ovarian cancers.

In time, Palmer said, the study will have data to report on other cancers, such as colon and lung.

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