To do so, they analyzed data from the Women’s Health Initiative, an observational study that examines the health of women aged 50 to 79. They then took a look at the assessments from the 16-year follow-up to find out which patients developed invasive breast cancer and if the cancer was estrogen receptor positive, which means the cancer cells are growing in response to hormone estrogen levels.
After evaluating the results, they found that 182 of the 3,460 participants developed breast cancer and that 142 of these patients were estrogen receptor positive. Furthermore, they discovered the risk of estrogen receptor positive breast cancer went up by 35 percent for every five kilogram increase of total body fat. This was the case even for those with a normal body mass index (BMI).
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"These findings will probably be surprising to many doctors and patients alike, as BMI is the current standard method to assess the risks for diseases related to body weight," co-author Andrew Dannenberg said in a statement. "We hope that our findings will alert women to the possibility of increased breast cancer risk related to body fat, even if they have a healthy weight."
Scientists did note they were unable to determine how body fat related to the possibility of breast cancer over time and that their investigations were limited to just to postmenopausal women and not other populations or cancers. However, they believe their results are groundbreaking.
"Our findings,” co-author Neil Iyengar said, “show that the risk of invasive breast cancer is increased in postmenopausal women with normal BMI and higher levels of body fat, meaning that a large proportion of the population has an unrecognized risk of developing cancer."
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