WEDNESDAY, Dec. 15 (HealthDay News) --Premenopausal women who
carry excess fat around their abdomen or have a large waist
relative to their hip size may face a higher risk for breast cancer
that is estrogen receptor (ER)-negative, new research reveals.
The research team noted that such body fat distribution was
linked more strongly to the risk for developing this particular
type of cancer than it was to a risk for ER-positive breast
cancer.
Body fat distribution of this kind was not associated with an
increased risk for breast cancer generally, according to the study,
published Dec. 15 in the
Journal of the National Cancer Institute.
Estrogen receptor (ER)-negative breast cancer means that the
cancer lacks receptors for the female hormone estrogen, so the
hormone does not stimulate the cancer to grow.
The research team, led by Holly R. Harris of Brigham and Women's
Hospital and Harvard Medical School in Boston, pointed out that
prior research had suggested that body fat composition (as
indicated by body mass index, or BMI) has a complex relationship
with cancer risk. For example, having a higher BMI has previously
been linked to a rise in the risk for postmenopausal breast cancer,
but not premenopausal breast cancer.
On the other hand, the researchers said that premenopausal women
who carry excess fat that wraps around organs in the abdominal
region are more likely to develop the pre-diabetic condition known
as hyperinsulinemia. Lab experiments have shown that insulin
receptors can promote the growth of breast cancer cells.
In their latest investigation, Harris and her colleagues focused
on data from more than 116,000 women who had been enrolled in the
Nurses Health Study II since 1989, including waist and hip
circumference, recorded in 1993.
The fact that ER-negative breast cancer was more strongly linked
to abdominal fat and the waist-hip ratio than ER-positive breast
cancer suggests, according to the researchers, that the means by
which body fat distribution influences cancer risk sidesteps
sex-hormone pathways.
The findings "may suggest that an insulin-related pathway"
related to abdominal fat is involved in the development of
premenopausal breast cancer, the authors wrote.
More information
The U.S. National Cancer Institute has more on
breast
cancer risk.