Multiple Benefits of Exercise for Breast Cancer Survivors

By Mary Hardy, MD. Dr. Hardy is Associate Director, UCLA Center for Dietary Supplement Research: Botanicals, and Medical Director, Cedars-Sinai Integrative Medicine Program, Los Angeles. Dr. Hardy reports no consultant, stockholder, speaker's bureau, research, or other financial relationships with companies having ties to this field of study.

Source: Ohira T, et al. Effects of weight training on quality of life in recent breast cancer survivors: The Weight Training for Breast Cancer Survivors (WTBS) study. Cancer 2006; [Epub ahead of print].

Abstract: Aerobic exercise training has been shown to have beneficial effects on quality of life in breast cancer survivors. However, the effects of weight training on psychological benefits are unknown. The authors sought to examine the effects of weight training on changes in quality of life and depressive symptoms in recent breast cancer survivors. A convenience sample of 86 survivors (4-36 months post treatment) was randomized into treatment and control groups. The primary outcomes were changes in quality of life (CARES short form) and depressive symptoms (CES-D) between baseline and month 6 in this randomized controlled trial. Over six months, the physical global quality-of-life score improved in the treatment group compared with the control group (standardized difference = 0.62, P = 0.006). The psychosocial global score also improved significantly in the treatment group compared with the control group (standardized difference = 0.52, P = 0.02). There were no changes in CES-D scores. Increases in upper body strength were correlated with improvements in physical global score (r = 0.32; P < 0.01) and psychosocial global score (r = 0.30; P < 0.01). Increases in lean mass were also correlated with improvements in physical global score (r = 0.23; P < 0.05) and psychosocial global score (r = 0.24; P < 0.05). The authors concluded that twice-weekly weight training for recent breast cancer survivors may result in improved quality of life, in part via changes in body composition and strength.

Comments

Despite an overall increase in the rate of new breast cancers, mortality rates have been steadily declining, about 1% a year.1 However, even though five-year survival rates now approach 90%, breast cancer survivors remain a population at risk. Despite the war on cancer and high-tech treatment options available, modifiable risk factors still account for the majority of cancer deaths today and need to be addressed as part of secondary prevention.2 Increased body weight and body fat are major risk factors for developing breast cancer, as well as increased morality, both for primary tumors and for recurrences.3,4 Unfortunately, breast cancer treatment itself often leads to increases in weight and a reduction of lean body mass.5 The majority of survivors do not meet physical activity levels generally recommended to the healthy population.6 Additionally, women report significant declines in quality of life during and after treatment. For all of these reasons, clinicians should strongly support interventions that increase patient quality of life and decrease their breast cancer risk. This month's abstract considers the possible benefits of an exercise regimen for women after completing breast cancer treatment.

Eighty-six post-treatment breast cancer survivors (4-36 months after treatment) were enrolled in a randomized control trial testing the effect of a six-month weight training program.7 Patients were randomized in such a way that participants in both groups had equal distributions of weight and body fat. For the first three months, the exercise group was supervised by a trainer and met in small groups twice weekly. They performed a set sequence of weight-training exercises, using both machines and free weights. Participants exercised on their own for the last three months. The control group received the same intervention six months after the treatment group. Quality-of-life measures, upper and lower body strength, as well as waist circumference, body weight, and body fat were measured.

The results from this study were encouraging. Significant differences were seen between the quality-of-life scores of the treatment vs. the control group (P = 0.02), but even larger improvements were seen in the physical quality-of-life scores (P = 0.006). These changes were associated with significant gains in upper body strength (P < 0.01) and increases in lean body mass (P < 0.05).

This was generally a well-conducted study with a number of strengths, including matching groups on key variables such as weight and body fat. There were a small number of dropouts (n = 7) and the intervention would not be difficult to generalize to a broader population.

However, some limitations should be mentioned as well. Given how the results were reported, it was difficult to tell how much, if any, weight the patients lost and exactly how much their percent body fat changed. Despite the strong statistically significant results in quality-of-life scores, the absolute amounts were small, so the clinical significance can be questioned. However, the robust response in the control group (50% improved one or other of their quality-of-life scores vs. 80% improved in treatment group) may have overestimated the response in the average breast cancer patient. It also is important to note that the participants anecdotally reported positive results of exercise, such as improvement in sleep and energy as well as decreases in body aches and fatigue, which are difficult to reflect in quantitative data.

Therefore, we should encourage our patients to attend to issues like exercise and weight control with the same vigor that we give to their conventional care. This type of intervention can improve quality of life and lower the risk of breast cancer recurrence as well as osteoporosis and postmenopausal heart disease. Include questions about exercise in follow-up visits with breast cancer survivors. Educate patients regarding the benefits of regular aerobic exercise and weight training. Explore barriers to exercise with inactive patients and make a plan to address these barriers. Finally, prepare a list of local facilities and follow up on your recommendations at the next visit. Lifestyle modification is important after breast cancer treatment and the primary care practitioner may be in an even better position than the oncologist to motivate the breast cancer patient. It may be that a walk a day, not an apple, will keep the doctor away!

References

1. Jemal A, et al. Cancer Statistics, 2006. CA Cancer J Clin 2006;56:106-130.

2. Danaei G, et al; Comparative Risk Assessment collaborating group (Cancers). Causes of cancer in the world: Comparative risk assessment of nine behavioural and environmental risk factors. Lancet 2005;366:1784-1793.

3. Lahmann PH, et al. A prospective study of adiposity and postmenopausal breast cancer risk: The Malmo Diet and Cancer Study. Int J Cancer 2003;103:246-252.

4. Kroenke CH, et al. Weight, weight gain, and survival after breast cancer diagnosis. J Clin Oncol 2005;23:1370-1378.

5. Freedman RJ, et al. Weight and body composition changes during and after adjuvant chemotherapy in women with breast cancer. J Clin Endocrinol Metab 2004;89:2248-2253.

6. Irwin ML, et al. Physical activity levels among breast cancer survivors. Med Sci Sports Exerc 2004;36:1484-1491.

7. Ohira T, et al. Effects of weight training on quality of life in recent breast cancer survivors: The Weight Training for Breast Cancer Survivors (WTBS) study. Cancer 2006; [Epub ahead of print].