WEDNESDAY, Dec. 7, 2011 (HealthDay News) -- Obese women with early stage breast cancer are less likely to survive than other women who are of normal weight, new research suggests.
Researchers from Baylor College of Medicine are slated to present their findings Wednesday at the 2011 San Antonio Breast Cancer Symposium.
"The findings add to the body of evidence indicating that obesity, in general, increases a patient's chance for having a worse prognosis," lead researcher Dr. Sao Jiralerspong, an assistant professor of medicine at Baylor, said in a symposium news release. "Obesity is a probable risk factor for worse breast cancer outcomes, and ours is the latest study to suggest it has an effect on treatment outcome as well."
In conducting the study, researchers analyzed the link between weight and treatment of 4,368 women with early-stage breast cancer over the course of 25 years. The investigators found that the participants who were overweight had survival rates that were similar to the women of normal weight, but those who were obese had an increased risk for shorter time to recurrence, and worse disease-free and overall survival.
Although the obese women who received no additional chemotherapy or endocrine therapy had worse outcomes, the study noted that obese patients who received chemotherapy fared significantly worse than normal-weight patients.
Jiralerspong suggested that biological factors linked to extra weight -- such as higher blood insulin and estrogen levels, inflammation and growth factors secreted by fat cells -- could help explain these findings.
The researchers also revealed, however, that obese women treated with endocrine therapy, primarily tamoxifen, had significantly better survival rates than women who were of normal weight.
"Finding that overweight patients have a better outcome than normal-weight patients after tamoxifen treatment is surprising. We are examining the possible reasons for this," noted Jiralerspong.
Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
In addition, more research is needed to understand how obesity affects treatment for breast cancer, particular since new treatments have been introduced since the study was conducted, the researchers added.
The U.S. National Cancer Institute has more about the link between obesity and cancer.