Risk factor for breast cancer
A decrease in total body fat has a greater effect on a reduction of sex hormones that are associated with breast cancer than a decrease in abdominal fat alone.
This underlines the importance of a healthy weight and physical exercise for overweight women. This has been shown in a trial among post-menopausal women by Dr. Evelyn Monninkhof, epidemiologist at the Julius Center of University Medical Center Utrecht. In 2016, over 13,500 women aged over 50 contracted breast cancer in the Netherlands.
"The study has shown that it is not a decrease in abdominal fat that is the key factor for reducing the risk of breast cancer due to hormones produced by the body, but rather a decrease in total body fat. This includes, for example, hip fat," Monninkhof explains.
Endocrine-Related Cancer today presents the results of her study ‘Association between changes in fat distribution and biomarkers for breast cancer’. The study was sponsored by the Dutch Cancer Society and Pink Ribbon.
In Monninkhof's study, 195 post-menopausal overweight women lost on average 5-6 kilos over 16 weeks, while 48 women stayed at the same weight. The sex hormone and leptin levels and the number of inflammation-related substances in the blood were compared to the levels from before the weight loss. The changes in total body fact and abdominal fat were measured using DEXA (body composition scan) and MRI scans.
After 16 weeks, an association could be demonstrated between a decrease in total body fat and favorable changes in a number of biomarkers for breast cancer, including sex hormones and leptin, while a decrease in abdominal fat was related more with a decrease in inflammatory markers.
Although previous studies had shown up conflicting associations between the risk of breast cancer and abdominal fat, this study used a more accurate method for determining fat distribution using scans instead of by just measuring the circumference of the waist and body mass index. As Monninkhof explains: "In the study period, we measured both the fat depots and the biomarkers twice; and we used more accurate DEXA measurements for total body fat, as well as MRI for belly fat.”
Monninkhof continues: "Our next step is to study how women could best tackle belly fat and total body fat. What nutrition and exercise programs will work the best for them? That way, they can lower the risk of breast cancer."