Exercise doesn't cure cancer, but it can help

[The Conversation] - Published on March 26, 2018 in Science and Society, Sports

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

Physical activity, long considered secondary

A brief historical overview. Before the 1980s, physical activity was of no interest to cancer specialists 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, 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 patients undergoing chemotherapy for breast cancer, thanks to an eight-week physical activity program conducted 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—making it tempting, 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 treatment began, or after treatment.
A review of the scientific literature published in 1999, however, confirms the significant impact of physical exercise on patients’ health-related quality of life. At the time, physical activity aimed to improve not only quality of life but also self-esteem, which had been undermined by aggressive treatments—particularly those causing hair loss.
Enjoying exercise was the key. Patients were therefore given the choice of what to do, with the idea that they would regain self-confidence and break out of isolation. This practice took place mainly at home, encouraged by healthcare professionals and a few pioneering oncologists. The health messages were fairly basic. Described as “hygiene and diet-related,” they could be summed up today with the phrase: “You need to move more when you have cancer.”

Reduce fatigue, pain, and anxiety

Starting in the 2000s, physical activity became a “supportive care” modality in its own right. In other words, it became part of “the care and support needed by patients throughout the course of their illness.” Official guidelines recommend starting it as soon as possible after the patient is diagnosed with cancer.

The goal is threefold. First, to reduce symptoms caused by treatments and the cancer itself, such as fatigue, pain, anxiety, depression, nausea, sleep disorders, lymphedema (swelling caused by poor lymph 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 (loss of confidence in one’s physical abilities). This deconditioning is a factor in poor prognosis, reduced treatment efficacy, and higher mortality.
Randomized controlled trials were then conducted, with converging conclusions showing a reduction in fatigue and anxiety-depressive symptoms, improved physical fitness, and prevention of deconditioning. A series of meta-analyses provided the highest level of evidence: 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, provides compelling evidence that supervised physical activity programs are beneficial for fatigue, based on 56 randomized controlled trials involving 4,068 patients undergoing cancer treatment. The program is supervised to ensure participant safety—for example, the risk of cardiovascular problems due to chemotherapy is taken into account. Supervision involves both adjusting the intensity to avoid exhausting the patient 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 National Cancer Institute (INCa) in 2017 guide 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 engage in APA mentioned in the 2014–2019 Cancer Plan.

Distinguishing false promises from genuine ones

In France, there is a vast but uneven array of physical activities offered by CLCCs, clinics, medical centers, sports organizations, cancer-focused 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 level. 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 remedy.
Clinical trials are beginning to be conducted worldwide on survival and the reduction of recurrences through physical activity, in combination with conventional cancer treatments, such as that of a team from the University of Alberta (Canada) on colon cancer , whose protocol was published in 2008. The first results will be available by 2020. In the meantime, the evidence is still insufficient to confirm 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 progress is needed to understand the mechanisms involved and to develop the best program for each patient, based on their tumor and lifestyle.
The hope that physical activity might one day help treat tumors is not entirely unfounded. But for now, what has been proven is that physical activity sufficiently regular and properly balanced helps improve patients’ quality of life, boost their overall health, reduce the side effects of treatments, and enhance the effectiveness 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.

Keywords: Health, Company, Sports