October 4, 2004
Dana-Farber, Brigham and Women's researchers study role of diet and exercise in breast cancer risk and recovery
Everyone knows that tobacco use is harmful and often lethal: Its combined contributions to lung cancer, heart disease, and pulmonary disorders result in 435,000 preventable deaths annually. Most people would be surprised, however, to learn that unhealthy diets and physical inactivity are catching up fast, currently causing an estimated 400,000 avoidable deaths a year.
Taking a cue from these striking statistics, researchers at Dana-Farber Cancer Institute and Brigham and Women's Hospital have begun looking closely at the role of a sensible diet and varying amounts of physical activity as factors in breast cancer risk and recovery from treatment.
It is already clear that women who avoid weight gain and are able to keep up an exercise program fare better in recovering from breast cancer treatment. Moreover, research by investigators at the Gillette Center for Women's Cancers at Dana-Farber is challenging traditional mantras that physical activity should be avoided to prevent lymphedema — a common and limiting side effect of breast cancer surgery.
Malcolm Robinson, MD
The most exciting news about healthy diets and exercise, however, is their potential to reduce the risk of breast cancer and the recurrences that are the greatest threat to long-term survival. While not yet proven, these ideas are being tested by Women's Cancers Program (WCP) investigators such as Malcolm Robinson, MD, who is pursuing the hypothesis that changes in a woman's body fat alter hormones that in turn raise or lower her breast cancer risk.
Dr. Robinson, director of Metabolic Support Services and the Program for Weight Management at Brigham and Women's Hospital, is focusing on hormones, including estrogen, ghrelin, insulin, and insulin-like growth factor (IGF-1). Their levels in the body are referred to as a "hormone profile."
Other research has demonstrated that elevated amounts of some of these hormones, which occur in overweight women, promote the growth of breast cancer cells in the laboratory. In the real world, it's known that overweight postmenopausal women are at higher risk for getting breast cancer in the first place, as well as for having the disease recur.
Dr. Robinson wants to find whether losing weight can lower these hormone levels, restore a normal hormone profile, and, in so doing, protect against cancer recurrences after successful breast cancer treatment. He cites a study published in the March 10, 2004 issue of The Journal of the American Medical Association that suggests lower caloric intake during youth may help protect against breast cancer.
"Generally, people lose weight from cancer therapy," says Dr. Robinson. "Breast cancer is unusual in that, due to treatment and other factors, patients often gain weight. If a woman's increase is significant, current data point to a poorer outcome after treatment."
He reasons that an abnormal hormonal profile may predispose a patient to recurrence, and has proposed a study of whether losing weight safely can have a protective effect. He is also trying to determine if eating a healthy diet is sufficient or if combining it with exercise will produce a more favorable hormonal profile.
"Data suggest that lowering cholesterol levels protects against future heart attacks," says Dr. Robinson. "We're trying to see if the same is true for correcting hormonal imbalances and breast cancer."
Next page: Bridging the gap
