June 16, 2010 (Chicago, Illinois) — In contrast to past advice to cancer patients to rest and avoid activity, the message now is to avoid inactivity. An expert panel convened by the American College of Sports Medicine (ACSM) has concluded that exercise training is safe during and after cancer treatments and can improve physical functioning, quality of life, and cancer-related fatigue.
The new ACSM guidelines urge cancer patients to be as physically active as possible both during and after treatment.
"The take-home message from the panel that put together the guidelines is to avoid inactivity during and posttreatment," said Kathryn Schmitz, PhD, MPH, associate professor of epidemiology and biostatistics at the University of Pennsylvania School of Medicine in Philadelphia. She presented the guidelines here at the American Society of Clinical Oncology 2010 Annual Meeting.
"Dozens of randomized controlled trials in a broad variety of patient populations have established the safety of exercise during treatment and the ability to go from being sedentary to completing 150 minutes of aerobic active over the course of even a single month," she said. "The risk–benefit leans heavily in the direction of getting patients moving and keeping them moving."
Exercise is an area that is gaining an increasing awareness in the cancer literature, noted Jennifer A. Ligibel, MD, who moderated the session where the guidelines were presented. Dr. Ligibel is from the Dana-Farber Cancer Center in Boston, Massachusetts.
"If you had done a search between 1950 and 1979 using the words 'exercise/physical activity' and 'cancer,' you would have found 12 references," said Dr. Ligibel. "But in 2009, there were almost 500, more than almost all of the years put together."
A growing number of reports have now shown that physically active individuals are less likely to develop a number of common cancers, including breast, colon, advanced prostate, some gynecologic cancers, she pointed out. "Evidence is mounting and consistent. There has been a growing number of reports that physically active individuals tend to do better after being diagnosed with cancer."
Much of the data, she pointed out, have been in breast cancer.
Even with a growing number of reports, exercise oncology is a field that is still in its infancy, explained Lee Jones, PhD, scientific director of the Duke Center for Cancer Survivorship at Duke University in Durham, North Carolina. "There are only about 80 or so studies focused on exercise in cancer, and that really isn't all that many, especially when compared to cardiovascular disease — where there are about 3500."
Evidence So Far Is "Very Promising"
Dr. Jones, who was approached by Medscape Oncology for independent comment, pointed out that the evidence thus far is very promising. "Higher levels of physical activity are associated with a significant risk reduction in mortality in cancer patients," he said. "And the research to date provides a platform to launch second-generation studies."
The next level of studies will need to focus on why exercise is an effective intervention in cancer patients, if it does have an effect on recurrence, and if so, the underlying mechanism, Dr. Jones explained.
It is hoped that future research will answer such questions as how the effect can be maximized, what intensity is needed, and if exercise is effective for some types of tumors and not others, he said.
The ACSM guidelines indicate that exercise is safe during treatment, but Dr. Jones acknowledges that that can be a difficult time for patients. "They are battling many things during that time, such as side effects, and exercise might be a little tougher," he said. "But exercise programs can be modulated to suit the patient; that is the premise of personalized medicine."
An exercise program is also dependent on where the patient was in life before their diagnosis. "Were they sedentary, athletic, exercising occasionally?" he asked. "That information is important in shaping an exercise program."
Dr. Jones stated that he would like to get to the point where exercise becomes part of the standard of care for cancer. "It may eventually reach the same standard as it is in cardiac disease," he said. "I see us building this evidence base."
Specific Risks Need to Be Addressed
In creating the guidelines, the authors focused on the adult cancers and sites (breast, prostate, hematologic, colon, and gynecologic) where the most evidence has been assembled, and reviewed the literature for multiple health outcomes.
The panel found that even though there are specific risks associated with cancer treatment that need to be considered when patients embark on an exercise program, the evidence is consistent that it can improve aerobic fitness, muscular strength, quality of life, and fatigue in cancer survivors.
There are some general medical assessments that are recommended prior to exercise, explained Dr. Schmitz. For example, an evaluation for peripheral neuropathies and musculoskeletal morbidities secondary to treatment is recommended, regardless of the time since treatment.
"This doesn't have to be done in the physician's office or by a nurse," she said. "Fitness professionals can ask if there are any changes in balance or whether the person has noticed any tingling or changes in the kinds of symptoms that go along with peripheral neuropathies."
Evaluations of fracture risk are also recommended for individuals who have undergone hormonal therapy, and those with known metastatic disease to the bone will require evaluation to discern what is safe before starting exercise, she added. "Patients with metastatic disease to the bone should have medical clearance before starting an exercise program."
Individuals with known cardiac conditions, whether secondary to cancer or not, also require a medical assessment before starting exercise.
"There is recognition that there is always a risk that metastasis to the bone or cardiac toxicity secondary to cancer treatments will be undetected in a portion of our 12 million cancer survivors out there," Dr. Schmitz said. "This risk will vary widely across the population of survivors, and is likely quite low in the great majority of people who are diagnosed at an early stage and grade."
It is therefore recommended that fitness professionals consult with the patient's medical team to determine the likelihood of this risk, she added. "What we concluded as a body, in order to reduce barriers to physical activity programs, is that requiring medical assessment for metastatic disease and cardiotoxicity for all survivors prior to exercise is not recommended."
"We chose to do this because we felt that the small risk in a small body of patients is probably less than the risk of telling patients that they shouldn't exercise until they are cleared," she explained. "The risk of inactivity for the great majority of people at low risk is greater than the small risk of putting someone in harm's way."
Research Gaps Remain
The panel found that there is consistent evidence that exercise training can lead to improvements in aerobic fitness, muscular strength, quality of life, and fatigue in breast, prostate, and hematologic cancer patients and survivors, but that the data for colon and gynecologic cancers are still too limited to lead to conclusions.
Multiple research gaps remain in this field, the panel notes. These include a need for greater specificity with regard to the dose-response effects of specific modes of exercise training on specific end points and within a broader range of populations, such as survivors of colon and gynecologic cancers.
They also urge fitness trainers who work with cancer survivors to learn as much as possible about the specifics of the cancer diagnosis and treatment to make informed safe choices with regard to exercise testing and prescription.
Cancer diagnosis and treatment effects numerous body systems that are required for and affected by exercise training, they conclude, and "because cancer treatments are increasingly customized according to specific tumor characteristics, fitness professionals may benefit from contacting the medical treatment team for more precise information regarding the treatments received."
Dr. Schmitz and Dr. Ligibel have disclosed no relevant financial relationships.
American Society of Clinical Oncology (ASCO) 2010 Annual Meeting: Presented June 6, 2010.