Study: Physical activity may decrease fatigue associated with cancer treatment

IN-DEPTH REVIEW OF RESEARCH

Study background

Exercise can improve quality of life and physical health for cancer survivors. However, only about one-quarter of cancer survivors meet recommended guidelines for physical activity. Several studies on physical activity and fatigue noted that many cancer patients abandoned prescribed exercise routines or refused to participate due to lack of time, motivation or confidence, feeling unwell or tired or not enjoying the type of exercise. Travel time to the exercise facility also decreased participation.

Physical activity that takes place in or near one’s home might boost participation in and adherence to exercise routines. This meta-analysis of 11 smaller studies looked at how home-based physical activity affects the possible side effects of cancer diagnosis and treatment—fatigue, depression and anxiety. While the effect of exercise on fatigue in cancer survivors has been studied before, this is the first review to compare the effectiveness of home-based to clinic-based approaches and to assess the effects of frequent counseling versus infrequent or no counseling.

Researchers of this study wanted to know

Researchers wanted to know how home-based physical activity interventions affect fatigue, depression and anxiety in adult cancer survivors.

Populations looked at in this study

In this meta-analysis, researchers reviewed 11 studies that included 1,066 participants:

• 94% were female
• 82% identified as Caucasian
• 56% had completed post-secondary education or higher
• 77% had a history of breast cancer
• 14% had a history of ovarian cancer
• 4% had a history of colorectal cancer
• 4% had a history of prostate cancer
• 1% had a history of an unspecified cancer type
• Mean age ranged from 53 to 69 years
• On average, participants had completed treatment 1.7 to 5.9 years before participating in the study.

Study design

The studies examined in this meta-analysis were randomized controlled trials that included cancer survivors who were age 18 or older and had completed cancer treatment. Also included were breast cancer survivors receiving adjuvant hormonal therapy. Nine studies looked specifically at fatigue, and two studies focused on depression and anxiety. Each study consisted of an intervention group that participated in the physical activity and a control group that did not change their exercise habits.

Participants in each study engaged in moderate- to low-intensity physical activity (such as brisk walking, biking, swimming or using exercise equipment) that was home-based and self-monitored. The interventions lasted from 6 weeks to 6 months, with most continuing for 12 weeks. In the nine studies looking at fatigue, participants reported their levels of fatigue immediately after the intervention. Some studies followed up with participants, asking them to again rate their fatigue at 3 months and 6 to 9 months after they had completed the intervention. Researchers compared the responses of individuals who performed the physical activity to those who did not receive any intervention. Some interventions included frequent counseling focused on exercise motivation, encouragement and problem-solving.

The researchers performed a random-effects meta-analysis on the nine fatigue-based studies to understand the effect of exercise on fatigue. Because some studies measured fatigue levels in different ways, the researchers needed to standardize the results of each study so they could compare the outcomes. To do this, they calculated the standardized mean difference (SMD) for each of the nine studies. The researchers calculated SMD by first finding the difference between fatigue scores for people in the intervention and control groups. Then, they divided that number by the standard deviation of all outcomes in the study. The resulting SMD is a standardized figure the researchers used to compare how well each study’s intervention worked to reduce fatigue.

Additional details about the study design can be found by searching the PROSPERO database using registration ID# CRD42020195618.

Study findings

Here is a summary of the methods and outcomes of the nine studies that looked at fatigue:

Can home-based physical activity interventions reduce fatigue for cancer survivors?

Of the nine studies that looked at fatigue outcomes:

• Meta-analysis showed a statistically significant reduction in fatigue among cancer survivors who participated in home-based physical activity interventions compared to those who did not participate in any intervention (controls). An SMD between 0 and 1 means the physical activity intervention worked to reduce fatigue, with numbers closer to 1 signaling a stronger effect of the intervention and numbers closer to 0 indicating a weaker effect.
  • Reduction in fatigue was statistically significant immediately after intervention: SMD=0.22
  • Reduction in fatigue was statistically significant three months after intervention: SMD=0.27
  • Reduction in fatigue was statistically significant six to nine months after intervention: SMD=0.31
• Frequent counseling led to better outcomes in fatigue reduction. Researchers think this might be because counseling promoted sustainable behavioral changes that led to increased exercise.
  • Frequent counseling: SMD=0.32
  • Infrequent or no counseling: SMD=0.05

Can home-based physical activity interventions reduce depression and anxiety in cancer survivors?

• No conclusions about the effect of exercise on these mental health measures could be made because only two studies analyzed these issues.
• The authors cite previous research that suggests exercise reduces depression and anxiety, and that both symptoms tend to occur with fatigue. One study showed that improving one symptom, such as fatigue, often improves the other two, so it’s possible that reducing fatigue through exercise also reduces depression and anxiety.

Are cancer survivors more likely to participate in and adhere to home-based interventions rather than clinic-based interventions?

• When the authors compared the participation and adherence rates in the meta-analysis to previous studies that included mainly clinic-based interventions, they found that participation and adherence were higher for at-home interventions.
  • Participation:
    • At-home: 55%
    • Clinic-based: 37–43%
  • Adherence:
    • Exclusively at-home: 77.9%
    • At-home and clinic-based: 65%
       

Strengths and limitations

Strengths

• While the effect of exercise on fatigue in cancer survivors has been studied previously, this analysis of the literature provides a more comprehensive view of how physical activity interventions, especially those that are home-based, affect fatigue symptoms.
• The effects of varying levels of counseling on survivors’ fatigue levels had not been studied. This review is the first to examine how frequent counseling influences fatigue in cancer survivors participating in a physical activity intervention.
• The researchers performed appropriate statistical analyses to properly support their conclusions.

Limitations

• The participants were mostly white female breast cancer survivors with high socioeconomic status so the results might not be generalizable for diverse populations with different cancer diagnoses.
• Participants knew to which group they were assigned (with or without physical activity). This could create behavioral changes or differences in self-reported fatigue symptoms that were not due to physical activity and would skew the results.
• The studies that reported fatigue reduction at 3 months and 6 to 9 months after the intervention were conducted by the same researchers, creating the possibility of procedural or researcher bias in these findings.
   

Context

After cancer treatment, 30 to 40 percent of people report experiencing fatigue. Other common symptoms are depression and anxiety. Since the 1990s, “exercise oncology” research has shown that physical activity plays a vital role in improving quality of life for cancer survivors. Previous studies looking at physical activity interventions have shown that exercise helps reduce survivors’ fatigue, depression and anxiety. Observational studies also suggest that cancer survivors who exercise more have lower levels of fatigue, depression and anxiety.

The authors of this study recognized a need to examine factors that contribute to participation in and adherence to prescribed exercise routines. According to previous studies, less than half of eligible participants choose to enroll in a physical activity intervention after cancer treatment, despite the proven benefits of exercise on physical and mental well-being. Survivors in earlier studies have cited barriers to participation, such as travel time to the facility, lack of motivation or confidence, feeling unwell or tired or not enjoying the type of exercise. Exercising at home might eliminate some of these barriers, but differences in participation and adherence rates for home-based versus clinic-based interventions had not been examined previously.

To address this gap in the data, the authors of this meta-analysis compared the home-based participation data to participation rates in previous studies that included clinic-based interventions. This was also the first study to analyze how the presence or absence of counseling affects exercise participation and fatigue symptoms. Overall, this meta-analysis confirms previous findings that exercise helps reduce fatigue for cancer survivors.
 

Conclusions

Low- to moderate-intensity exercise such as brisk walking, biking, swimming or using home-exercise equipment is effective at reducing fatigue in cancer survivors. People are more likely to form a habit of exercising and adhere to physical activity interventions when the activity is home-based rather than in a clinic. In addition, interventions that include frequent counseling focused on behavioral change lead to a more drastic decrease in fatigue levels than those that are paired with infrequent or no counseling.

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posted 8/1/22