14 DAY TRIAL // A recent study concluded that there is a link between body fat distribution and the increased risk of estrogen receptor (ER)-negative breast cancer.
Holly R. Harris, Sc.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues, wanted to see what was the exact relation between the distribution of body fat and the risk for premenopausal breast cancer.
To do so, they carried out a prospective study among women in the Nurses' Health Study II – 116,430 women who have been followed up since 1989.
In 1993, the women filled in a questionnaire asking them to measure and report their waist and hip circumference.
According to statistics, there was no link between waist circumference, hip circumference or the waist to hip ratio, and the risk of developing breast cancer.
On the other hand, the researchers did find that waist circumference and the waist to hip ratio (abdominal adiposity), was more strongly connected to a risk of ER-negative breast cancer than with a risk of ER-positive breast cancer.
After seeing that body fat distribution was more linked to ER-negative breast cancer, the researchers concluded that body fat could influence breast cancer risks through sex hormone-independent pathways.
They said that body fat is associated with hyperinsulinemia (pre-diabetes), and added that insulin receptors are expressed in most breast cancers and they stimulate the growth of breast cancer cells in vitro.
“These findings may suggest that an insulin-related pathway of abdominal adiposity is involved in the etiology of premenopausal breast cancer,” the authors add.
Previous studies proved that the relation between BMI and breast cancer risks depends on the menopausal status – a high BMI is linked to the risk of postmenopausal breast cancer.
Intra-abdominal fat surrounding organs has been linked to metabolic and hormonal changes, as well as premenopausal breast cancer risk, but prospective studies have came up with conflicting results, without looking at the role of hormone receptor status.
This is why it is important to know that body fat distribution does not play an important role in the incidence of every subtype of premenopausal breast cancer.
The research was published in The Journal of the National Cancer Institute.