Exercise may improve chemotherapy completion rate in breast cancer patients [Новость добавлена - 25.09.2007]

Encouraging patients who are undergoing adjuvant chemotherapy for breast cancer to take either aerobic or resistance exercise might increase the chance that they will complete a full course of chemotherapy, according to the surprise findings of a study published in the Journal of Clinical Oncology.

For patients with breast cancer, taking a course of drugs after having surgery to remove the tumour---an intervention known as adjuvant chemotherapy---improves the chances of long-term survival, but this treatment may also adversely affect the patient’s quality of life by causing fatigue and decreasing physical functioning. Few interventions have been shown to prevent these declines and the quality of the studies examining this issue are generally poor, involving only small groups of patients and mixing together several different drug regimens.

There is, however, some evidence to suggest that exercise may improve quality of life in patients undergoing cancer treatment. To test this idea further, and to work out whether one type of exercise works better than another, Kerry Courneya and colleagues from several institutions in Canada initiated a multi-centre randomised trial---the START trial or Supervised Trial of Aerobic Versus Resistance Training. The study examined the independent effects of aerobic and resistance exercise on quality of life, fatigue, psychosocial functioning, physical fitness, body composition, and chemotherapy completion rates, along with side-effects. "We hypothesized that both aerobic exercise training and resistance exercise training would be superior to usual care for the patient-rated outcomes," the authors explain.

Between 2003 and 2005, the researchers recruited 242 patients with stage I to IIIA breast cancer who were just beginning their first-line adjuvant chemotherapy, having already undergone surgery. These individuals were randomly assigned to one of three groups: usual care (n=82), supervised resistance exercise (n=82) or supervised aerobic exercise (n=78). All completed a questionnaire, physical fitness test, and a bone mineral density scan at the time of enrollment.

Participants were asked to exercise for the duration of their chemotherapy, beginning 1 to 2 weeks after starting chemotherapy and ending 3 weeks afterwards. Warm-up and cool-down periods consisted of 5 minutes of light aerobic activity and stretching. The aerobic group was asked to exercise three times per week on a cycle machine, treadmill, or elliptical trainer for 15 minutes each session in weeks 1 to 3, increasing by 5 minutes every 3 weeks until the duration reached 45 minutes at week 18. The resistance group did two sets of eight to 12 repetitions of nine different exercises three times a week. The exercises included leg extension, leg curl, leg press, calf raises, chest press, seated row, triceps extension, biceps curls, and modified curl-ups. Resistance was increased by 10% when participants completed more than 12 repetitions. Patients in the usual care group did not start any additional exercise programme. Outcomes that were rated by the patients themselves, including cancer-related quality of life, fatigue, and psychosocial functioning, were measured at the beginning of the study, in the middle of chemotherapy, and after the exercise programme had been completed. Chemotherapy completion rates were also obtained for all the patients.

Analysing the results, the researchers found that neither resistance nor aerobic exercise significantly improved quality of life. But they observed that undertaking exercise seemed to contribute to improved self esteem among trial participants and, surprisingly, to the chemotherapy completion rate. Self-esteem was superior in both the exercise groups compared with usual care and the chemotherapy completion rate, as measured by relative dose intensity, was higher in both exercise groups: 78% and 74% of patients undertaking resistance and aerobic exercise, respectively, received 85% of their planned dose, compared with just 66% in the usual care group.

"The failure of our exercise interventions to significantly improve cancer-specific quality of life may be, in part, a result of the wide variability in quality of life change scores we found during chemotherapy," suggest the authors. However, they add: "Cancer care professionals should consider recommending either aerobic or resistance [exercise] to breast cancer patients receiving chemotherapy."