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Every month, hundreds of women clad in pink hats and ribbons traverse great distances, often covering more than 20 miles a day, to raise money for breast cancer research. Walkers sweat and struggle through blisters, sore muscles and fatigue, in defiance of a disease that strikes 1 in 8 women in their lifetime.
But these women may be doing more than bolstering research efforts-they may be reducing their own risk of developing cancer, step by step. Research indicates that exercise may have a positive effect on breast cancer prevention, recurrence and survival rates in postmenopausal women.
Although a 3-day walk isn't enough to stave off breast cancer, a healthy amount of exercise over the long term can reduce primary and secondary cancer risk. 1 The American Cancer Society guidelines, which are based on a meta-analysis of cancer studies, recommend at least 30 minutes of moderate to vigorous exercise at least 5 days a week. 2
And doing more is even better, says Rebecca G. Smith, MD, MS. "Forty-five minutes of exercise a day can confer additional protective benefits," says Dr. Smith, an assistant professor of physical medicine and rehabilitation and chief of cancer rehabilitation at the
University
of
Pennsylvania
in
Philadelphia
.
For rehab clinicians, it's important to understand the connection between physical activity and breast cancer risk. With this information, you can pass along vital, perhaps life-saving, information to your patients. And as new studies come out each day, it's even more important to know which information is statistically significant across multiple, long-term clinical trials. Becoming familiar with well-researched trends in prevention and treatment allows you to provide patients with the best chance for a healthy life.
Preventive Measures
 Physical activity and being overweight have been shown to be independent factors related to breast cancer risk--activity reduces risk, while being overweight raises risk. Consensus documents conclude that there's approximately a 30 percent protective effect from regular exercise in postmenopausal women, says Kathryn H. Schmitz, PhD, MPH, an assistant professor at the University of Pennsylvania School of Medicine. So when it comes to breast cancer, even overweight women can benefit from physical activity; being sedentary and overweight can be double trouble.
While researchers are unsure of exactly what, if any, effect daily exercise has on premenopausal women, the incentive to exercise prior to menopause remains high. Literature looking at animal models suggests that exercise can positively impact longevity and cancer risk at the chromosomal level, says Dr. Smith. The implications of such research underscore the importance of a life-long emphasis on physical activity for overall health and wellness. These recent findings suggest that the physiological effects of exercise are exerted on numerous organ systems and molecular pathways.
In addition, postmenopausal women who've gained at least 20 pounds since age 18 have a higher risk of breast cancer, says Susan Brown, RN, MS, citing two studies. 3,4
While exercise alone may not reduce cancer risk prior to menopause, it can help women maintain a consistent, healthy weight throughout life, which does impact risk.
And, women who are overweight before menopause tend to be overweight after menopause-a known risk factor for breast cancer, says Brown, director of health education for Susan G. Komen for the Cure, a non-profit organization that raises money for breast cancer research, education and health services.
Treatment Implications
It stands to reason that women who are in good shape when they receive a diagnosis of breast cancer will have an easier time recovering from surgery, radiation and chemotherapy than those who are sedentary. Where you start from a fitness standpoint impacts what happens during treatment, says Dr. Schmitz.
When you consider the fact that muscles begin to atrophy with as little as 1 week of bed rest, it's apparent that the ability to get moving after treatment is a top priority.
However, several obstacles to physical activity commonly affect women after breast cancer treatment. Consider the following barriers that may hold patients back.
Fatigue. One of the most common side effects of all breast cancer treatments, fatigue hits women hard during the recovery period. But not all fatigue is related to chemotherapy, says Dr. Smith.
Clinicians should assess patients for underlying medical problems, such as anemia, an electrolyte imbalance or a thyroid problem. If fatigue seems to be treatment-related, work with patients to devise a gradual, progressive exercise program.
Fatigue is often the reason women shun physical activity during recovery. But regular activity can reduce fatigue and feelings of depression, says Brown.
Pain. Women who undergo surgery or radiation often deal with pain and tenderness in the treatment area.
Scar tissue can build up near the shoulder joint after surgery, which restricts movement and causes pain. Radiation can lead to cording, which is characterized by extreme pain and swelling due to radiation-induced nerve damage.
Both interventions cause patients to guard the area and refrain from movement on the affected side. "The effect is the same as if the patient had a traumatic injury to the area," says Dr. Schmitz.
However, movement is essential to prevent pain from becoming worse over time. Dr. Schmitz recommends gentle range of motion and strengthening exercises as soon as 24 hours after surgery. "You have to get the soft tissue moving and keep it soft," she says.
Lymphedema. Women who have breast cancer are at a significantly higher risk of developing lymphedema, due to the potential for lymph node damage during surgery and harsh cancer treatments.
"In the past, we cautioned women who were at risk for lymphedema about exercise in the affected area, but new literature suggests that exercise is not as big a risk as we may have thought," says Brown. While activity improves blood flow, which increases metabolites and lymphatic flow, women can exercise safely with the approval of their clinicians and a few precautions, such as wearing a compression garment, avoiding extreme temperatures, staying hydrated and stopping before becoming over-fatigued.
For women who already have lymphedema, a slow, progressive exercise progam should be employed on the affected side. Due to older treatment beliefs, "it's not a standard of care yet, but it should be," says Dr. Smith. Research has linked lymphedema to increased body mass index, so exercise is an important method for controlling weight and diabetes risk in this population. 5
It's worth the effort to help patients overcome the obstacles of fatigue, pain and lymphedema risk in order become active again. The benefits of exercise go beyond controlling the weight gain that's commonly associated with breast cancer treatments.
Consider that women who've been irradiated in the chest wall area may be at increased risk for heart disease. Cardio-toxic chemotherapy agents can also raise the possibility of heart disease. In addition, cancer drugs can reduce bone density, which can lead to early onset of osteoporosis. For these reasons, exercise is a vital component of a recovery plan.
The question of whether physical activity can reduce the chance of breast cancer recurrence is still up in the air. "There are too few studies for us to feel like this is a slam dunk," says Dr. Schmitz, but early returns suggest a positive link.
What researchers do know is that long-term physical activity raised the overall survival rate in breast cancer survivors in a 20-year study-a promising finding for women who want to take back control of their health. 6
"There are so many risk factors we can't control, like genetics, getting older and family history of breast cancer, but physical activity is something we can control," says Brown.
It's up to rehab clinicians to spread the word.
For a list of references, go to http://www.advanceweb.com/rehaband click on the references toolbar.
Diana Olsen
Friedman is associate editor of ADVANCE . She can be reached at dolsen@merion.com
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