It’s well documented that breast cancer and obesity are commonly co-incident; even overweight seems to increase the risk of a woman’s developing the disease — and that’s particularly true for postmenopausal women. One hypothesis is that an excess of adipose tissue produces more estrogen than would typically be found in a woman who is post-menopause, and that this is related to breast cancer causation. This theory relates to breast cancers that are hormone-sensitive.
So consideration of this connection between breast cancer and excess adiposity has led some researchers to question whether a reduction of body weight, and presumably fat tissue, by women who have had breast cancer, would prevent a recurrence of the disease.
This is the basis for a large new study — a collaboration between the Dana-Farber Cancer Institute and the Fitbit company. The goal is to determine if weight loss prevents the recurrence of hormone-sensitive breast cancer in obese/overweight women.
This Breast Cancer Weight Loss Study (BWEL) will include 32,000 overweight or obese women who have been diagnosed with early stage breast cancer. Each participant will receive FitBit devices: a fitness tracker that collects activity and heart rate information throughout the day; a scale that tracks weight, BMI, lean body mass and body percent fat, as well as access to proprietary software "which offers personalized video-based exercise experiences on mobile devices." All these will link to an online dashboard to monitor progress and help the women stay on track.
Participants will be randomized to a two-year long weight loss study. They will get a weight-loss intervention, plus a health education program that provides information on breast cancer-related topics. Those women randomly selected to be in the control group will get only the health education program without the weight-loss intervention.
“The increased risk of cancer recurrence linked to excess body weight," said Dr. Jennifer Ligibel, lead investigator on the study and a breast oncologist at Dana-Farber, "threatens to limit our progress in treating breast cancer and preventing women from dying from this disease.”
Results of this study will not be known for years. While two years of a weight-loss program will hopefully result in the participants losing substantial amounts of weight, that fact alone will not answer the main questions. First, will the women who lose weight maintain that loss after the two-year intervention has ended? Second, will we see a decrease in recurrence of their cancers in the women who lose weight? Since cancer recurrence can occur years after treatment is over, these women will have to be monitored frequently.
In the interim, advising the overweight or obese to participate in exercise and diet changes is not a bad idea.