More fat in your midsection could increase your risks for breast cancer

(CNN) -- Excess body fat levels in post-menopausal women have been linked to a higher risk in breast cancer, according to a new study.

Published in the medical journal JAMA Oncology, researchers saw that those women who carried more weight were at double the risk of developing estrogen-dependent breast cancer.

These cancers, called ER-positive breast cancer in the study, occur when the receptor proteins attach to the estrogen hormone and rely on it to grow. Nearly 3500 post-menopausal women between 50 and 79 years old had their body composition measured at the beginning of the study. Of those women, 146 developed ER-positive breast cancer.

Researchers found that those with an 11-pound increase in overall body fat, had a 35% increased risk of getting that cancer. And if they carried that 11-pounds mainly in their midsection, their risk went up to 56%.

Increased fat in their torso also increased their risk of developing invasive breast cancer by 46%. This was even the case with those that fell under a normal body mass index.

The study authors say this signals a shift from simply looking at one's BMI, to instead focusing on where the person's excess fat is concentrated.