Birth Weight Linked to Breast Cancer Risk in Black Women.
African American women have a markedly higher breast cancer mortality rate than their White counterparts, and their rate of breast cancer diagnosis is on the rise.
Now, a new study led by School of Public Health researchers suggests that African American women who were particularly small or large at birth, or born to older mothers, may be at increased risk of breast cancer.
The study was published in Cancer Causes & Control.
“Low birth weight is more common among African American babies, due to the higher prevalence of preterm birth—and giving birth to large babies has become more common in general in the US population in recent years,” says doctoral student Lauren Barber, the study’s lead author. “Both of these associations, although weak, could contribute to the increasing incidence of breast cancer in African American women.”
Previous research in primarily White populations has suggested that birth weight may be related to breast cancer risk, but few studies have explored this relationship among Black women, says Barber, who is also a trainee in the Susan G. Komen Graduate Training in Disparities Research Program.
With support from the Susan G. Komen Foundation, Barber and her colleagues in BU’s Slone Epidemiology Center analyzed data from their Black Women’s Health Study, a long-term, prospective study of 59,000 Black women across the United States followed since 1995.
For the new study, the researchers looked at data on the births and infancies of the participants, including birth weight, mother’s age, birth order, preterm birth, twin/triplet status, and having been breastfed.
Compared to women who weighed between 5 pounds 8 ounces and 8 pounds 13 ounces at birth, the researchers estimated that women with birth weights below this range were 19 percent more likely to be diagnosed with breast cancer, while women with birth weights above this range had a 26-percent increased risk.
“These findings suggest the importance of continued work on reducing the disparities that lead to higher rates of low weight births among African Americans,” says study co-author Julie Palmer, professor of epidemiology and a Slone Epidemiology Center faculty member.
The researchers also found that women whose mothers were 35 years of age or older when they were born had a higher risk of breast cancer than women whose mothers were under 20 years old. This association was only for estrogen receptor (ER) positive breast cancer, the most common type of breast cancer, not ER negative breast cancer, a particularly aggressive form of breast cancer that is more common in Black women than White women.
The study was co-authored by Lynn Rosenberg, professor of epidemiology and a Slone faculty member; Tracy Battaglia, associate professor of epidemiology; and Kimberly Bertrand, assistant professor of medicine at the School of Medicine and a Slone faculty member.