Reference
Schmitz KH, Ahmed RL, Troxel AB, et al. Weight lifting for women at risk for breast cancer–related lymphedema: a randomized trial. JAMA. 2010;304(24):2699-2705.
Design
Randomized, controlled equivalence trial.
Participants
One hundred fifty-four breast cancer survivors 1 to 5 years post unilateral breast cancer, with at least 2 axillary lymph nodes removed and without clinical signs of arm lymphedema at study entry.
Study Intervention
Women in the weight-lifting intervention group received a 1-year membership to a community fitness center. For the first 13 weeks, women were instructed twice weekly for 90 minutes by certified fitness professionals. Exercises targeted upper body (seated row, supine dumbbell press, lateral or front raises, bicep curls, and triceps pushdowns) and lower body (leg press, back extension, leg extension, and leg curl). Three sets of each exercise were performed at each session, with 10 repetitions per set.
Weight was increased for each exercise by the smallest possible increment after 2 sessions of completing 3 sets of 10 repetitions with no change in arm symptoms. After 13 weeks, participants continued unsupervised exercise twice weekly for the rest of the year.Control group subjects were not exercising at study entry or throughout the 1-year length of the trial.
Outcome Measures
The primary outcome was lymphedema onset, defined as a 5% or more increase in inter-arm swelling. Water volume displacement was used to measure arm volumes at baseline and 12 months. Evaluations for lymphedema occurred after report of a change in symptoms or if indicated by measurements taken during monthly safety evaluations or each 3-month interval limb assessment.
Key Findings
The proportion of women in the weight-lifting group experiencing lymphedema was 11% (8 of 72) and 17% (13 of 75) in the control group, yielding a relative risk reduction of 35% for the intervention (95% CI: -17.2%–5.2%; P for equivalence=0.04).
In a planned secondary analysis of women with 5 or more lymph nodes removed, lymphedema incidence in the weight-lifting group was 7% (3 of 45) and 22% (11 of 49) in the control group, giving a relative risk reduction of 70% for the intervention (95% CI: -18.6%– -11.4%; P for equivalence=0.003).
Practice Implications
Prior studies looking at upper body exercise among breast cancer survivors support the findings of this study.1-4 This is the first well-controlled and sufficiently powered clinical trial to demonstrate that weight training does not increase the incidence of lymphedema after axillary node dissection and may significantly reduce the risk among breast cancer survivors who have had 5 or more axillary lymph nodes removed. Because of the concern over lymphedema and of the current list precautions, which include avoidance of lifting heavy objects,5 patients commonly avoid arm exercises. These findings provide good evidence that weight training does not increase risk and may significantly decrease the incidence of lymphedema in our highest-risk patients, which provides clarity for clinicians making recommendations for the prevention of lymphedema in women after breast cancer surgery.
Since exercise is helpful in facilitating weight loss and the maintenance of ideal body weight, we can see how it serves to mitigate the incidence of lymphedema in this population via multiple mechanisms.
According to the authors, “These results are consistent with the well-defined hormetic effect of exercise training.” In other words, gradual increases in physiological stress enhance the body’s ability to respond to infection and injury through improvements in microcirculation, oxidative stress, and inflammation.6
It’s known that overweight women (BMI > 25) are at significantly increased risk for lymphedema after breast cancer surgery.7-9 Since exercise is helpful in facilitating weight loss and the maintenance of ideal body weight, we can see how it serves to mitigate the incidence of lymphedema in this population via multiple mechanisms. This data, along with numerous studies showing improvement among breast cancer patients who exercise in quality of life measures,10 response to treatment,11 and potentially survival after treatment12 provides further support for the broad salubrious effects of exercise in women treated for breast cancer.
