Abdominal Fat Affects Breast Cancer Survival

A new study from researchers at the University of North Carolina at Chapel Hill provides evidence that excess abdominal fat can affect breast cancer survival.

The researchers followed 1,254 women ages 20 to 54 diagnosed with invasive breast cancer between 1990 and 1992. Women with a waist-to-hip ratio greater than 0.80, which indicates higher concentrations of abdominal fat, were 52 percent more likely to die of breast cancer in the next nine years compared to those with ratios at or below 0.80, after adjusting for the effects of obesity, the researchers said. People with a high waist-to-hip ratio typically have an apple shape, with fat concentrated in the abdomen.

The study also shows obesity has a detrimental effect on breast cancer survival, the researchers said. Women with a body mass index greater than 30, which indicates obesity, were 48 percent more likely to die during the nine year study period than women of ideal weight. If the study participants were both overweight (body mass index greater than 25) and had a waist-to-hip ratio above 0.80, their risk of dying increased by 92 percent.

"These results demonstrate that obesity, particularly abdominal fat, decreases a woman's chance of surviving breast cancer, even if she is premenopausal at the time of diagnosis," said Dr. Marilie Gammon of UNC's Lineberger Comprehensive Cancer Center, and a professor of epidemiology in UNC's School of Public Health. "Our goal is to identify factors that will enhance survival among women with breast cancer. Maintaining a healthy weight throughout adult life is something women can do to improve their survival."

The study appears in the Oct. 15 issue of the journal Cancer Epidemiology Biomarkers & Prevention. Funding was provided by the National Cancer Institute and Public Health Service grants from National Institutes of Health.

Lead author Page Abrahamson, a postdoctoral researcher at the Fred Hutchinson Cancer Center in Seattle, Wash., said excess abdominal fat may influence breast cancer prognosis in the same way obesity affects the odds of developing breast cancer. These influences include increased exposure to estrogen or developing insulin resistance. Abrahamson conducted the study as a graduate student in UNC's School of Public Health.

To measure the effects of abdominal fat and obesity on breast cancer survival, Abrahamson and her colleagues followed 1,264 premenopausal women diagnosed with invasive breast cancer between 1990 and 1992 living in metropolitan Atlanta or a five-county region of New Jersey. Shortly after diagnosis, interviewers asked participants to report weight and height at 20 years old and the year before diagnosis. The interviewers also measured body fat indicators such as waist and hip circumference.

Study co-authors are from: Emory University, Atlanta, Ga.; Mount Sinai School of Medicine, New York, N.Y.; the federal Centers for Disease Control and Prevention, Atlanta, Ga.; Fred Hutchinson Cancer Research Center, Seattle, Wash.; and the National Cancer Institute, National Institutes of Health, Bethesda, Md.