Women who are obese when they are diagnosed with early-stage breast cancer are at a greater risk of dying of their disease than women of normal weight. That is the result of a study conducted by researchers at the Fox Chase Cancer Center in Philadelphia, Pa. and presented today at the 46th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Atlanta, Ga.
The study compared the outcome data of obese, overweight and normal-weight women with early-stage breast cancer treated with conservation surgery (lumpectomy) and radiation therapy.
"We have demonstrated a significant association between obesity and adverse breast cancer outcome in patients with early-stage breast cancer," explained Penny Anderson, M.D., a radiation oncologist at Fox Chase and lead investigator of the study. "Despite being diagnosed with early stage disease, which is more commonly cured, obese women more often developed metastatic disease and more often died."
The influence of obesity on breast cancer outcome has been uncertain, especially in early-stage breast cancer patients. Previous studies show that obesity is a risk factor for the development of breast cancer, but these prior studies have reported contradictory results regarding the influence of obesity on outcome in breast cancer patients.
For this study, researchers analyzed the data of 2,010 patients from 1978 to 2003 with stage I/II breast cancer who were treated with lumpectomy, lymph-node dissection and radiation therapy with or without chemotherapy. Patients were categorized into three groups according to their weight: normal (452 patients) overweight (857 patients) and obese (701).
"Our results show a statistically significant difference between obese women and the other groups," said Anderson.
The five-year rates for overall survival were 92 percent, 92 percent and 88 percent for the normal-weight, overweight and obese groups, respectively. Five-year rates of distant metastasis were 7 percent for women of normal weight, 6 percent for overweight women and 10 percent for the obese group.
"Because the prevalence of obesity increases with age, as does the risk of breast cancer, interventions that enhance weight control may have a substantial effect on breast cancer outcome," Anderson said.
Fox Chase Cancer Center was founded in 1904 in Philadelphia as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at http://www.fccc.edu or call 1-888-FOX CHASE.
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