Obesity May Raise Breast Cancer Death Risk for Some
Study found younger, obese patients with estrogen receptor-positive disease were more likely to die
Among the 20,000 women who had ER-positive breast cancer and had not yet gone through menopause, the death rate from breast cancer was 34 percent higher in those who were obese compared to those of normal weight. That risk increase, for instance, would change a 10-year risk of death from breast cancer from 15 percent to 20 percent.
The findings seems counterintuitive, Pan said, because obesity substantially raises the level of estrogen in the blood only after menopause.
The researchers took into account other factors, such as tumor characteristics and the type of treatment given, and the link still held. Pan said he can't explain the link. While the study found an association between obesity and risk of death from certain breast cancers at certain ages, it did not prove a cause-and-effect link.
The standard definition of obesity was used -- a body-mass index (BMI) of 30 or higher. A woman who is 5-foot-4 and weighs 175 has a BMI of 30.
The study was funded by Cancer Research UK, the UK Medical Research Counsel and the British Heart Foundation.
"This study forces us to pay attention to obesity in premenopausal women," said Dr. Courtney Vito, a breast surgeon and assistant clinical professor of surgical oncology at City of Hope Comprehensive Cancer Center in Duarte, Calif.
This study strongly suggests that women need to pay attention to weight control, regardless of their menopausal status, Vito said.
Weight is a risk factor that can be controlled, Vito said. "Once you are 50 and have breast cancer, you can't go back and breast-feed [which reduces risk]," she said. Nor can women change family history or other risk factors, she said.
But "being overweight is something you can take control of," Vito said.