Causes of High Incidence of Breast Cancer in African-American Women Identified
ScienceDaily (Aug. 16, 2011) —
Investigators from the Boston University’s Slone Epidemiology Center have
reported findings that may shed light on why African American women have a
disproportionately higher risk of developing more aggressive and
difficult-to-treat breast cancers, specifically estrogen and progesterone
receptor negative (ER-/PR-) cancers.
The study, which appears online in Cancer
Epidemiology, Biomarkers & Prevention, found that high parity
(giving birth to two or more children) was associated with an increased risk of
ER-/PR- cancer, but only among women who had not breastfed.
The findings were based on the ongoing Black
Women’s Health Study, which has followed 59,000 African American women by
biennial questionnaire since 1995.
In 14 years of follow-up, 318 women developed
breast cancers negative for estrogen and progesterone receptors (ER-/PR-),
while 457 developed breast cancers with estrogen and progesterone receptors
(ER+/PR+). Giving birth to two or more children was associated with a 50
percent increase in the incidence of ER-/PR- breast cancer, but the association
was not present among women who had breastfed.
According to the researchers, the results for
ER+/PR+ breast cancer, which is more common among white women, were strikingly
different. High parity was associated with a decreased risk, and breast feeding
had no influence on that association.
“The higher incidence of ER-/PR- breast
cancer in African American women may be explained in part by their higher
parity and lower prevalence of breastfeeding relative to white women,”
explained lead author Julie Palmer, ScD, MPH, a senior epidemiologist at the
Slone Epidemiology Center and a professor of epidemiology at Boston University
School of Public Health.
“Our results, taken together with recent
results from studies of triple negative and basal-like breast cancer, suggest
that breastfeeding can reduce risk of developing the aggressive,
difficult-to-treat breast cancers that disproportionately affect African
American women,” she said.
This study was supported by a grant from the
National Cancer Institute of the National Institutes of Health.
For further information click:
http://www.sciencedaily.com/releases/2011/08/110816133103.htm