Common Changes in Body Composition in Breast Cancer Patients May Be Preventable With Exercise
DURHAM, N.C. -- Increasing or maintaining activity levels may help premenopausal patients avoid the weight gain common with chemotherapy for breast cancer, researchers from Duke Comprehensive Cancer Center and elsewhere reported Monday in the May issue of the Journal of Clinical Oncology.
The researchers said weight gain is a significant psychological burden for premenopausal breast cancer patients and is also a potential health problem itself. Excess weight is associated with heart disease, diabetes, stroke and other conditions in the general population. Until now, many oncologists assumed patients were eating too much, but this study, the largest of its kind, says activity is the key.
"Our study does not support over-eating as a cause for weight gain in premenopausal breast cancer patients receiving chemotherapy," said lead author Wendy Demark-Wahnefried, associate research professor in the Department of Surgery. "Chemotherapy patients did not eat more than they did before treatment or when compared to patients not getting chemotherapy. Instead, reduced activity level appears to be responsible."
"Even with concerns about immune system suppression, it's important that patients not cloister themselves throughout their treatment," added co-author Dr. Kelly Marcom, a Duke medical oncologist specializing in breast cancer. "This research should be a motivator for women getting chemotherapy for breast cancer to stay as active as they can."
The researchers measured and compared diet, activity, resting metabolism and body composition in premenopausal, early-stage breast cancer patients who received only localized treatment -- surgery with or without radiation treatment -- to those who also received chemotherapy to help minimize the risk of recurrence. The oneyear study of 53 patients was funded by the National Cancer Institute.
"Weight gain is a substantial problem for breast cancer patients getting chemotherapy, particularly for premenopausal women," Marcom said. "Weight loss is generally more associated with other cancers, including lung and pancreatic cancers, but it's not nearly as common with breast cancer."
While most analyses of breast cancer patients have found a significant weight increase for chemotherapy patients compared to those not receiving chemotherapy, in this study the weight gain itself was not as striking as its composition, the researchers said.
"In the general population, weight is gained in both lean muscle tissue and fat," said Demark-Wahnefried. "In premenopausal breast cancer patients receiving chemotherapy, however, we saw an increase in adipose tissue, while lean tissue stayed the same or even decreased -- so patients became 'fatter' even if their weight stayed the same. This wasn't the case for patients getting localized treatment only."
Because this increase in body fat is accompanied by reduced activity, exercise represents a possible avenue of prevention, said the researchers.
"In a small pilot study we've seen that specific exercises in a clinic-based setting can stop this weight gain and muscle loss from happening," said Demark-Wahnefried. "Through a study we're starting soon, we will see whether a home-based exercise intervention can provide similar benefits."
At the annual meeting of the American Society of Preventive Oncology in March, Demark-Wahnefried reported that a structured exercise program prevented the typical weight gain and muscle loss in nine premenopausal breast cancer patients receiving chemotherapy.
Developed in conjunction with exercise physiologists at the Duke Center for Living, the program emphasized aerobic activity, specialized strength training focused on the lower body and a low-fat diet with lots of fruits and vegetables, she said.
The exercise study participants lost an average of 2.1 kilograms (4.6 pounds), increased their lean mass by 0.1 kg (0.22 pounds), and lost 1.9 kg (4.2 pounds) of fat tissue during the six-month program. By comparison, the 36 chemotherapy patients in the current JCO study gained an average of 2.2 kg (4.8 pounds), lost 0.1 kg (0.22 pounds) of lean tissue, and gained 2.0 kg (4.4 pounds) of fat.
"We were able to stop the weight gain with specific exercises and a low-fat, high-fruit and vegetable diet," said Demark-Wahnefried. "The new, homebased study, which uses adapted exercises and a video and written manual for instruction, will determine the relative importance of exercise, diet recommendations and telephone counseling."
While reduced activity is one culprit in the weight gain, more work is necessary to see whether the chemotherapy drugs actually alter the way the body uses or stores calories. The researchers also said that since chemotherapy frequently induces menopause or menopause-like symptoms in premenopausal patients, additional study is necessary to examine the role of amenorrhea, or lack of menstrual cycles, in the weight gain.
Other co-authors on the study are Drs. Bercedis Peterson, Lawrence Marks and Kimberly Blackwell of Duke, Dr. Eric Winer of the Dana Farber Cancer Institute in Boston and Drs. Barbara Rimer and Noreen Aziz of the National Cancer Institute.