Exercise doesn't cure cancer, but it can help
Today, there is a lot of talk and writing about the benefits of exercise in fighting cancer—all too often without sufficient scientific evidence. However, an analysis of the available studies allows patients to know what to expect from their efforts. While exercise does not cure cancer, certain physical activity programs can help—and there is evidence to support this.
Gregory Ninot, University of Montpellier
Exercise is becoming a key tool in the fight against cancer. Organizations encourage patients to practice karate or tai chi. Specialized cancer centers, such as the Curie Institute, organize group exercise or endurance classes. Organizations are setting up exercise sessions via videoconference, such as V@si. And sports federations—such as the tennis federation—offer special programs for this group.
Following an adapted physical activity program is one of the many “alternative therapies” that can be used to treat this disease, in addition to conventional treatments. Its benefits will be discussed at the scientific conference on theEffectiveness of Non-Pharmacological Interventions in Cancer, which will take place on March 23 in Montpellier, organized by the CEPS Platform.
Physical activity, long considered secondary
A brief historical overview. Before the 1980s, physical activity was of no interest to cancer care professionals in France. Priority was given to treatments—surgery, radiation therapy, and chemotherapy—while everything else was considered secondary. And this was entirely justified, given the progress that had been made in the field.
Specialized hospitals were established in major cities—the Cancer Treatment Centers (CLCC)—to handle the growing influx of patients diagnosed at increasingly early stages and to house technical facilities in appropriate settings.
Between 1980 and 2000, research teams launched the first clinical studies, particularly in Canada and the United States. For example, a prospective trial published in 1999 by an American scientist demonstrated an improvement in the quality of life of 27 breast cancer patients undergoing chemotherapy, thanks to an eight-week physical activity program carried out at home.
Early studies, primarily on breast cancer
Most of the studies available during this period were pilot studies, with numerous methodological limitations. Breast cancer was the predominant focus—and the temptation was great at the time to extrapolate the results to all cancers. The physical activities analyzed varied greatly from one another. And they were initiated at different stages of patient care: immediately after the diagnosis was announced, before the start of treatment, and after treatment.
However, a review of the scientific literature published in 1999 confirms the significant impact of physical exercise on patients’ health-related quality of life. At the time, the goal of physical activity was to improve not only quality of life but also self-esteem, which had been undermined by aggressive treatments—particularly those causing hair loss.
Enjoying physical activity was the key. Patients were therefore given the freedom to choose their own activities, with the aim of helping them regain self-confidence and break out of isolation. This activity took place primarily at home, encouraged by healthcare professionals and a few pioneering oncologists. The health messages were fairly basic. Described as “hygiene and diet” advice, they could be summed up today with the phrase: “You need to be more active when you have cancer.”
Reduce fatigue, pain, and anxiety
Starting in the 2000s, physical activity became a “supportive care” measure in its own right. In other words, it became part of “the care and support necessary for patients throughout the course of their illness.” Official recommendations state that it should be started as soon as possible after the patient is diagnosed with cancer.
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The goal is threefold. First, to reduce symptoms caused by treatments and by cancer itself, such as fatigue, pain, anxiety, depression, nausea, sleep disturbances, lymphedema (swelling caused by poor lymphatic circulation), and neuropathy (nerve damage). Second, to improve overall health, physical fitness, and body composition—that is, to promote muscle mass gain at the expense of fat mass, particularly abdominal fat. Finally, to prevent physical deconditioning, that is, the vicious cycle leading to physical inactivity with all its physiological (such as muscle atrophy) and psychological (such as loss of confidence in one’s physical abilities). This deconditioning is a factor associated with a poor prognosis, reduced treatment efficacy, and higher mortality.
Randomized controlled trials were then conducted, yielding consistent findings showing a reduction in fatigue and anxiety-depressive symptoms, an improvement in physical fitness, and the prevention of deconditioning. A series of meta-analyses provided the highest level of evidence, including those from 2005, 2006, 2009, and 2011.
Adjust the intensity of the exercise appropriately so as not to exhaust the patient
A recent meta-analysis, published in 2012, which is particularly compelling, concludes that a supervised physical activity program is beneficial for fatigue, based on 56 randomized controlled trials involving 4,068 patients undergoing cancer treatment. The program is supervised to ensure participants’ safety—for example, by taking into account the risk of cardiovascular problems caused by chemotherapy. Supervision involves both adjusting the intensity to prevent patient exhaustion during treatment and maintaining their participation over time.
Currently, other studies are being conducted on the post-cancer period to encourage people to continue regular weekly physical activity in line with recommendations. General principles established bythe French National Cancer Institute (INCa) in 2017 provide a framework for these practices. Two other institutions, Inserm and the French National Authority for Health (HAS), will publish their recommendations this year.
These initiatives are part of a broader movement toward “prescription exercise,” which has been in effect by decree since March1, 2017. This involves the medical prescription of adapted physical activity (APA) programs for people with chronic illnesses. Added to this is the encouragement to participate in APA mentioned in the 2014–2019 Cancer Plan.
Distinguishing False Promises from True Ones
In France, there is a vast but uneven array of physical activities offered by CLCCs, clinics, medical centers, sports associations, cancer organizations, companies in the sports and health sector, startups, and independent practitioners. This proliferation of offerings is sometimes accompanied by promises that go beyond scientific knowledge, even going so far as to hold out the prospect of a cure or the prevention of recurrence.
To date, it is not possible to predict such outcomes on an individual basis. Only cohort studies—which track hundreds of patients over time—provide insights into the role of physical activity in recovery, and even then, only in terms of probability. For example, an analysis of 24 cohorts from different countries, comprising a total of 35,622 patients, indicates a 38% reduction in cancer-related mortality risk for breast cancer, colorectal cancer, and prostate cancer, according to research by a Canadian team published in 2016. This does not make exercise an anti-cancer cure.
Clinical trials are beginning to be conducted worldwide on survival rates and the reduction of recurrences through physical activity, in combination with conventional cancer treatments—such as a study by a team at the University of Alberta (Canada) on colon cancer , whose protocol was published in 2008. The initial results are expected by 2020. In the meantime, the evidence is still insufficient to conclude that engaging in physical activity at a specific intensity and in a specific manner can influence the progression of cancer or its recurrence.
Influencing immunity, metabolism, inflammation, and neuropsychology
The underlying idea is to slow the progression of the tumor and help prevent recurrence by specifically stimulating the individual’s immune, metabolic, inflammatory, and neuropsychological functions through targeted physical activity. Further scientific and clinical research is needed to understand the mechanisms involved and to develop the best program for each patient, based on their tumor and lifestyle.
Hopes that physical activity might one day help treat the tumor are not entirely unfounded. But for now, what has been proven is that physical activity sufficiently regular and well-balanced It helps improve patients’ quality of life, enhance their overall health, reduce the side effects of treatments, and enhance the effects of certain treatments. That’s already a lot.
Gregory Ninot, Professor of Health, Psychology, and Sports Science, University of Montpellier
The original version This article was published on The Conversation.