Exercise Proven, but Underused, for Breast Cancer Fatigue

Kate M. O'Rourke


December 15, 2017

A growing body of evidence demonstrates that exercise can help patients with breast cancer manage their fatigue, even in the metastatic setting.[1,2,3,4,5] This message, however, is not getting to those who need it.

"Fatigue in breast cancer is a big, big problem, and we don't have good answers for it. Exercise is the best recommendation we have," said Charles Loprinzi, MD, Regis Professor of Breast Cancer Research at Mayo Clinic in Rochester, Minnesota.

Studies have consistently shown that exercise reduces breast cancer fatigue.

According to Karen Mustian, PhD, MPH, a professor of surgery at the University of Rochester Medical Center in Rochester, New York, it wasn't until the last 5 or 10 years that fatigue was recognized as a real phenomenon. "More and more, what we are learning is that there are real physiologic changes in a person's body that are accompanied by the disease and subsequent radiation therapy, chemotherapy, surgery that actually cause this kind of fatigue," said Dr Mustian. These include changes in proinflammatory cytokines.[6,7,8]

Up to 90% of patients treated with radiation and up to 80% of those treated with chemotherapy experience fatigue.[9] Cancer-related fatigue is characterized by feelings of tiredness, weakness, and lack of energy and is distinct from the normal drowsiness experienced by healthy individuals in that it is not relieved by rest or sleep.[9] It occurs as a consequence of the cancer itself and as a side effect of cancer treatment, although the precise underlying pathophysiology is still being worked out. "Fatigue can happen all throughout the entire cancer trajectory," said Dr Mustian.

Exercise More Effective Than Drug Therapy

For the last 10 years or so, studies have consistently shown that exercise reduces fatigue in the metastatic and nonmetastatic breast cancer setting.[5] Studies show that most current pharmaceutical interventions tend to ameliorate symptoms of fatigue only temporarily, and exercise and behavioral interventions are consistently more effective at managing symptoms and perhaps addressing the underlying etiology.[5] "Simply resting and trying to find a miracle drug are not the answer for [cancer-related fatigue]," said Dr Mustian. "The first-line therapies are lifestyle interventions that involve trying to stay active and mobile. We use the word 'exercise,' but really, it's simple walking."

Simply resting and trying to find a miracle drug are not the answer.

"Walking is the best thing they can do," said Anna Schwartz, PhD, an expert on cancer and physical activity at Northern Arizona University in Flagstaff, Arizona. She believes that doctors need to get more involved with promoting exercise for breast cancer. "One of the biggest barriers is getting practitioners to recommend exercise and give specific advice on what to do," said Dr Schwartz.

As patients gets more treatment, they tend to get more profound fatigue. Dr Schwartz thinks of the fatigue in two parts, fatigue from the actual physical effects from the treatment and disease and then a different sort of fatigue from having to come to the clinic all the time for treatments. "What we see with patients is they progressively become more fatigued, particularly if they don't do anything physically active to counteract that," said Dr Schwartz. "We believe that a lot of that fatigue is related to being debilitated."

Exercise helps with fatigue and has a variety of other beneficial effects, including helping people emotionally. "Exercise helps with mood; and if you are in a better mood, you would be able to better tolerate being fatigued and tolerate your treatments a little bit better," said Dr Schwartz.

Discussing in Clinic

The majority of cancer patients report that their physicians do not discuss exercise programs, and they wish that their physicians would initiate these conversations.[2] While doctors have limited time, said Dr Schwartz, they can reinforce to patients that they should be exercising regularly and have nursing or other staff talk to patients about how to exercise. Dr Schwartz said that she writes prescriptions for exercise for patients with breast cancer, following the American College of Sports Medicine (ACSM) guidelines that note that exercise is generally safe for most cancer survivors, and inactivity should be avoided.[10] The ACSM guidelines recommend 150 minutes of moderate or 75 minutes of vigorous aerobic activity per week and 2 days per week of resistance training (eg, with exercise bands or light weights).[10]

The majority of cancer patients report that their physicians do not discuss exercise programs.

For patients with metastatic disease, a multidisciplinary team effort by medical professionals including the oncologist, physical therapist, and orthopedist is needed for appropriate management.[2] "If somebody has a bone metastasis, one would adapt the exercise, so we don't cause injury," said Dr Schwartz. Survivors with lymphedema, peripheral neuropathy, and breast reconstruction need to follow specific precautions.[10] Many believe that providing health professionals with the training and tools needed to provide adequate recommendations to their patients is essential to improving patient outcomes.[10]

Dr Mustian has published the 5 As of applied exercise oncology that can help physicians guide discussions about exercise:

  • Ask about exercise habits;

  • Advise based on a review of the benefits of exercise and ACSM exercise guidelines for cancer survivors;

  • Assess a patient's exercise limitations and contraindications;

  • Assist with exercise barriers; and

  • Arrange for a medical consult and an exercise oncology professional consultation.[2]

A variety of studies provide evidence that supervised exercise reduces cancer-related fatigue, and many clinicians believe that it must be implemented in breast cancer rehabilitation settings.[1] In a meta-analysis of nine studies involving 1156 patients, supervised aerobic exercise was more effective than conventional care in improving cancer-related fatigue among breast cancer survivors (standardized mean difference [SMD]=-0.51).[1]

According to Fatima Cardoso, MD, director of the Breast Unit of Champalimaud Clinical Center in Lisbon, Portugal, and chair of the ABC Global Alliance, the effects of exercise in early breast cancer have been well studied, but very little research around the world has focused on its role in advanced breast cancer. This is why she applauded a recent study presented at the Advanced Breast Cancer Fourth International Consensus Conference by Eduardo Oliveira, PhD, a professor of exercise physiology at University of Porto, Portugal.[4] The study involved 15 women, aged 34-68 years, who were being treated for metastatic breast cancer. All of the women did not exercise when they joined the study. Eight women took part in a 12-week exercise program, which included an hour of exercise twice a week (aerobic, weight-bearing, and rehabilitation exercises). The remaining seven patients continued to receive normal care.

In the study, all women were tested at the beginning and end of the 12-week period to measure their cardiovascular fitness, defined as the amount of oxygen their bodies used while doing aerobic exercise (VO2 max). Patients in the exercise cohort had an average increase in their V02 max of 12.3% compared with 2.7% in the control group. Dr Oliveira said that this suggests that women who are exercising are becoming better at transporting oxygen around their bodies, with their hearts pumping blood and their muscles using oxygen more efficiently. For fatigue, there was a 14.4-point reduction among women exercising, compared with 2.2 points in women in the control group. Exercise also improved pain and quality of life. All women completed the full 12-week program, suggesting that the program was well tolerated.

Dr Oliveira believes that there is a need for more sports scientists to do research into cancer and exercise. Among the many unanswered questions is proper dose. "We have to individualize exercise to each person, and we don't yet know how hard you should push one person versus another person," said Dr Schwartz.

Dr Schwartz, Dr Mustian, Dr Cardoso, Dr Oliveira, and Dr Loprinzi have no relevant disclosures.


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