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 Cancer Center in Philadelphia 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).
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 seven percent for women of normal weight, six percent for overweight women and ten 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.
MEDICA.de; Source: Fox Chase Cancer Center