October 4, 2004
Dana-Farber, Brigham and Women's researchers study role of diet and exercise in breast cancer risk and recovery
Bridging the gap
Jennifer Ligibel, MD, checks in on clinical trial participant Barbara Schoeman.
Jennifer Ligibel, MD, a medical oncologist in the WCP, is focusing on exercise as a way of lowering levels of one hormone, insulin, with the hope that these reductions will decrease breast cancer recurrences.
"We know that women who are overweight at the time of breast cancer diagnosis have a higher risk of recurrence than lean women, but the reasons for this are not clear," she says. "Recent evidence suggests that high insulin levels, which are common in overweight women, may be involved in the increased risk of breast cancer recurrence."
Previous studies have shown that certain types of exercise can reduce insulin levels, but most of these studies have not included many female patients, let alone women who have had breast cancer.
"We know exercise is good for women for many different reasons. Some studies suggest that it may help prevent breast cancer from occurring in the first place," says Dr. Ligibel.
"Unfortunately, chemotherapy decreases a person's energy during treatment, and many people stop exercising completely," she explains. "Often, patients don't return to good exercise patterns after chemotherapy is completed, even if they once had them." This inactivity can lead to weight gain and higher insulin levels, which might also increase the risk of the cancer coming back.
Dr. Ligibel is working with a group of nondiabetic breast cancer survivors who will undertake a 16-week exercise program. The question is whether supervised strength-training sessions with a gym trainer and unsupervised endurance exercise (such as walking, jogging, or bicycling) will reduce the group's insulin levels.
The pilot study, with funding from the Lance Armstrong Foundation and the American Society of Clinical Oncology, will enroll 100 women over two to three years. They must have completed treatment (both chemotherapy and radiation) at least six months previously. Measurements of insulin, glucose levels, and body fat before and after the exercise programs will determine whether there have been changes in breast cancer survivors; if so, a larger study will follow to determine if exercise leads to longer survival.
"Exercise has benefits all through treatment and afterwards," says Dr. Ligibel. "It's an investment in a woman's health and hopefully will prove to lower her risk of dying from breast cancer."
Michelle Holmes, MD, assistant professor of medicine at Harvard Medical School, concurs. Her team drew on participants in the Nurses' Health Study to look at how physically active women were in the two years after being diagnosed with breast cancer. In general, the more they exercised, the lower their risk of dying from the disease.
"We were able to show that even a moderate amount of physical activity improved the odds of surviving breast cancer," says Dr. Holmes. "It is especially heartening for women who are recovering to know that the benefit is as readily accessible as walking for 30 minutes on most days of the week."
Next page: First-hand recovery experience
