Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline Summary and Q&A
2American Society of Clinical Oncology, Alexandria, VA
3Northwell Health Cancer Institute and Feinstein Institutes for Medical Research, New York, NY
Guidelines regarding the important role of exercise, diet, and weight management have been developed for the general adult population and cancer survivors,1-4 but less attention has been focused specifically on patients who are undergoing cancer treatment. Addressing the role of these health behaviors in treatment toxicity, quality of life, and cancer control will provide oncologists and patients with additional tools for preserving or improving health and wellness during cancer treatment. The evidence base for this guideline consisted of randomized controlled trials (RCTs) and systematic reviews of RCTs that involved patients undergoing active treatment with systemic antineoplastic therapy or radiotherapy or who were in the perioperative period. This body of evidence not only allowed for some clear conclusions on the part of the ASCO Expert Panel but also highlighted important knowledge gaps and priorities for further research (Fig 1).5
Exercise has concrete and significant benefits for adult patients with cancer who are undergoing systemic therapy or radiation and for patients with lung cancer in the perioperative period. Exercise reduces toxicities of cancer treatment, such as fatigue and decline in cardiorespiratory fitness, physical function, and strength. Exercise also improves quality of life and mood. Although there was insufficient evidence to determine whether exercise improves chemotherapy completion rates or dose intensity or reduces the risk of cancer recurrence or mortality, evidence clearly demonstrates that exercise helps to support patients undergoing cancer treatment. On the basis of this evidence, we believe that exercise should now become a routine part of the treatment of adults during active therapy.
Aerobic and resistance exercise should be recommended for adult patients with cancer receiving active treatment, including chemotherapy and radiation. Exercise may also be recommended in the perioperative period for patients with lung cancer. The panel reviewed available evidence in an attempt to develop more specific guidance regarding the frequency, intensity, and duration of exercise, but ultimately concluded that available evidence did not provide sufficient granularity to develop specific exercise prescriptions of this type for patients in the active treatment period.
The panel also recognized that patients may need different kinds of programs to help them increase exercise. Although many patients undergoing cancer treatment will be able to exercise safely on their own, some patients will need supervised exercise programs or cancer rehabilitation to help overcome functional limitations because of treatment toxicity or comorbidities. National efforts are focusing on building algorithms and decision-support tools to point to the most safe, feasible, and effective intervention for a given patient.6,7
This guideline is an important first step in establishing exercise as the standard of care for patients receiving treatment for cancer. In addition, although studies have suggested that recommendations from oncology providers can help increase exercise behaviors, many patients will need longitudinal support to help foster long-term behavior change. Oncology providers will need training on how to provide exercise counseling and/or facilitate appropriate referrals to team members.8 Although many patients will be able to exercise on their own in their homes or in community-based settings, the creation of a network of clinical or supervised exercise programs will be needed for others, allowing clinicians to refer patients to programs that fit their needs. These programs will need to be offered at a variety of hours and reimbursed by insurers with minimal cost sharing to overcome patient barriers to participation and ensure that all patients have equal access to exercise as a part of their cancer care.
The literature review for this guideline revealed a number of significant gaps in the evidence base. There were strikingly few studies that focused on the impact of a diet intervention—and almost none on a weight loss intervention—during treatment on any kind of outcome. In addition, in the trials that were available, there was considerable heterogeneity in the diets being tested and many studies were of low quality. This lack of evidence made it impossible to develop the same type of recommendation on the basis of data from RCTs for diet and weight loss during active cancer treatment that had been used to create the exercise recommendations.
The panel was quite conflicted on the best course of action given this lack of evidence. Observational data suggest that a plant-based diet and maintaining weight in a healthy range are associated with lower risk of cancer and better outcomes in some malignancies.2 There are also many other health benefits of a plant-based diet and weight control on a myriad of health outcomes, including lower risk of cardiovascular and metabolic diseases, comorbidities prevalent in patients with cancer that contribute to inferior outcomes. A number of panel members felt that, in the absence of clear evidence regarding optimal diet or weight loss strategies during active cancer treatment, patients with cancer should be advised to follow guidelines developed to support general health. However, after vigorous debate and many iterations of the guideline, the absence of clear evidence supporting a particular diet or weight loss/maintenance strategy in patients currently receiving cancer treatment or in the perioperative period led the panel to conclude that there was not sufficient evidence to provide a specific recommendation. However, a note was added to the recommendations stressing that lack of research testing diet and weight interventions led to the inability to make specific guidance, rather than trials showing no effect, and that oncology providers should not be discouraged from speaking to their patients about diet and weight management on the basis of the guideline report.
There is significant interest in understanding the impact of diet and weight on cancer outcomes. Without high-quality evidence, patients may be at risk of pursing a diet that is unlikely to provide benefit—or may even be harmful. We hope that this guideline is seen as a call to action, highlighting the critical need for a significant investment in definitive research testing the impact of high-quality diets and prudent weight loss strategies on important outcomes such as treatment toxicity and cancer control in individuals undergoing cancer treatment.
Many patients look to make changes in diet after cancer diagnosis. As discussed previously and described in detail in the guideline, there are few randomized trials testing specific dietary interventions during cancer treatment. Nutritional needs of patients during cancer treatment vary on the basis of the treatment regimen, nutritional status of the patient, and comorbidities. Some popular diets, such as ketogenic diets and fasting, could potentially limit nutrients that influence an individuals' ability to tolerate treatment and maintain functional status. Although some trials are ongoing, there are little safety data regarding the implementation of these types of dietary patterns in patients receiving cancer treatment. Patients who are interested in dietary change after cancer diagnosis could be counseled as to the lack of data supporting benefit of ketogenic diets, fasting, and other popular diets at this time.
Conception and design: All authors
Collection and assembly of data: All authors
Data analysis and interpretation: All authors
Manuscript writing: All authors
Final approval of manuscript: All authors
Accountable for all aspects of the work: All authors
The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated unless otherwise noted. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/op/authors/author-center.
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No potential conflicts of interest were reported.
Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline was developed and written by Jennifer A. Ligibel, MD; Kari Bohlke, ScD; Anne M. May, PhD; Steven K. Clinton, MD, PhD; Wendy Demark-Wahnefried, PhD, RD; Susan C. Gilchrist, MD, MS; Melinda L. Irwin, PhD, MPH; Michele Late; Sami Mansfield, BA; Timothy F. Marshall, PhD, MS; Jeffrey A. Meyerhardt, MD, MPH; Cynthia A. Thomson, PhD, RD; William A. Wood, MD, MPH; Catherine M. Alfano, PhD.
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