Even being moderately overweight is linked to a higher risk of breast cancer recurrence, finds a new study published Monday in the journal Cancer.
Despite the best treatment, researchers at Montefiore Medical Center found, the higher a woman's body mass index (BMI), the higher her risk of developing breast cancer again after treatment. Moreover, women who were obese at time of breast cancer diagnosis had approximately a 30 percent higher risk of recurrence and a nearly 50 percent higher risk of death than those who were normal weight at time of diagnosis.
"Treatment strategies aimed at interfering with hormonal changes and inflammation caused by obesity may help reduce the risk of recurrence," said lead study researcher Dr. Joseph Sparano, associate chairman of medical oncology at the Montefiore Einstein Center for Cancer Care, in a news release today.
The idea that extra body fat may lead to an increased chance of breast cancer coming back makes sense, as this fat causes hormonal changes as well as increased inflammation. The increase in hormone and inflammation can cause some breast cancer cases to spread -- and even to recur.
"As fat cells also are producers of estrogen, obese persons may not have the same degree of estrogen suppression from anti-estrogen therapies used to treat and prevent breast cancer," said Dr. Jennifer Litton, assistant professor of oncology at the University of Texas MD Anderson Cancer Center in Houston.
This study found that despite optimal treatment, including chemotherapy and hormonal therapy, the increased body mass index -- which usually corresponds to the body's fat content -- significantly increased women's risk of cancer recurrence and death. Additionally, the more obese the patient is, the more likely they are to have breast recurrence and death from this cancer.
Dr. Clifford Hudis, chief of the Breast Cancer Medicine Service at Memorial Sloan-Kettering Cancer Center in New York, is part of a team that has investigated the connection between weight and cancer incidence. He said that this new study adds yet more weight to the idea of this connection.
"It is clear that there are myriad additional negative consequences of obesity including increased risks of non-hormonally mediated cancers," Hudis said.
In the new study, the type of breast cancer that was increased was hormone receptor-positive, the most common type of breast cancer that accounts for two-thirds of all breast cancer cases in the United States and worldwide.
"We absolutely believe that weight loss is critical to prevention of breast cancer, as well as recurrence," said Dr. Jay Brooks, oncologist at Ochsner Clinic Foundation and Hospital in Baton Rouge, La. "I tell my patient that next to taking [chemotherapy] treatments, the simple most important thing they can do is lose weight."