Researchers confirm the risk of triple negative breast cancer in obese women who are also physically inactive, and suggest additional mechanisms other than estrogen.
The researchers have determined an association between physical activity, obesity and triple negative breast cancer, a breast cancer subtype which is defined by a lack of progesterone, estrogen and HER2 expression. About 10 – 20% of all breast cancers are triple negative breast cancers and are related to a very poor prognosis because of an absence of targeted drug treatments.
Breast cancer isn’t just a single disease. It’s a complex combination of a number of diseases. This subtype is biologically very different from other breast cancers, and it’s unique that the researchers discovered a relationship with triple negative breast cancer.
A connection between obesity and higher postmenopausal breast cancer risk has long been observed by epidemiologists, in addition to a reduced risk that accompanies increased physical activity. An association between estrogen and adipose tissue is believed to play a role in this risk.
Data from the women who participated in the Women’s Health Initiative (WHI) was analyzed. The researchers evaluated recreational physical activity as well as BMI (body mass index) in the women having triple negative breast cancer as well as the women having estrogen receptor-positive breast cancer.
The results revealed that those having the highest BMI had a 35% higher triple negative breast cancer risk and a 39% higher estrogen receptor positive breast cancer risk. Women who noted high rates of physical activity had a 23% reduced triple negative breast cancer risk and a 15% reduced estrogen receptor positive breast cancer risk.