A new study funded by the National Cancer Institute and the California Breast Cancer Research Fund tells us that obesity not only raises the risk of developing breast cancer, but is now shown to increase the chances of dying from it.
According to a press release, “The study, conducted in nearly 4,000 breast cancer survivors, found that obesity is strongly linked to death due to breast cancer. In particular, overweight or obese women with a history of estrogen receptor-positive breast cancer, but not those with estrogen receptor-negative cancer, had a higher risk of dying of their disease,” said the study's lead author, Christina Dieli-Conwright, PhD, assistant research professor at City of Hope National Medical Center in Duarte, Calif.
The National Cancer Institute estimated that obesity and physical inactivity account for 25 to 30 percent of several major cancers – colon, breast, endometrial, kidney, and cancer of the esophagus.
The National Cancer Institute also reported that in 2002, about 41,000 – or 3.2 percent – of all new cases of cancer in the U.S. were estimated to be due to obesity. And a recent report from the Institute estimated that, in the U.S., 14 percent of deaths from cancer in men and 20 percent of deaths in women were due to overweight and obesity.
Dieli-Conwright and her team recently presented their study’s findings at The Endocrine Society's 93rd Annual Meeting in Boston.
Their research involved participants of the large California Teachers Study who, between 1995 and 2006, received a diagnosis of invasive breast cancer - cancer that has spread beyond the breast ducts. Of the 3,995 women studied, 262 died of breast cancer through 2007, the authors reported in their abstract.
The researchers defined obesity as a body mass index (BMI, in kg/m2) of 30 or higher. The authors obtained BMI, a measure of height and weight, from questionnaires showing each participant's self-reported height and weight at baseline and at age 18. Baseline was the beginning of the study and was near, but necessarily at, diagnosis, according to Dieli-Conwright.