Key messages
- Compared to no yoga, yoga after anticancer therapy probably reduces cancer-related fatigue slightly in the short term (up to 12 weeks after doing yoga).
- We do not know if yoga during anticancer therapy relieves short-, medium-, or long-term cancer-related fatigue compared to no yoga.
- More research is needed to understand (1) if the effects of starting yoga after anticancer therapy persist beyond 12 weeks, and (2) what are the effects of doing yoga before starting and during cancer treatment.
What is cancer-related fatigue?
Cancer-related fatigue is a feeling of extreme tiredness that lasts for a long time. It can be caused by cancer, cancer therapy, or both. Cancer-related fatigue affects the body and mood, and makes it hard to perform regular activities. It is stronger than just being tired, and does not go away by resting.
How is cancer-related fatigue treated?
Clinical guidelines (documents that give healthcare professionals advice on the best ways to care for people, based on the latest research and expert opinion) recommend physical exercise to improve cancer-related fatigue. Physical exercise affects cancer-related fatigue by influencing biological and psychological processes. But it is unclear what types of exercise may be most beneficial. It is thought that yoga may reduce cancer-related fatigue and improve the quality of life of people with cancer because of how yoga combines physical exercise/movement with breath control, mental focus, and body awareness. This review is one of a suite of five reviews exploring different kinds of exercise for cancer-related fatigue.
What did we want to find out?
We wanted to find out if yoga improves cancer-related fatigue and quality of life in adults (18 years and older). We also wanted to learn if there were any adverse events in the studies; that is, unwanted events that caused harm to participants.
We investigated the effects of yoga in the short term (up to 12 weeks after doing yoga sessions), medium term (between 12 weeks and 6 months after), and long term (more than 6 months after doing yoga sessions).
What did we do?
We searched for studies that compared yoga with no yoga in adults with any cancer. We included yoga done before, during, or after initiation of anticancer therapy. We included multiple types of yoga, including Hatha (a gentle, slow yoga focusing on basic poses and breathing) and Dru yoga (a flowing style that includes movements, breathing, and relaxation).
We compared and summarised the results of the studies, and rated our confidence in the evidence, based on factors such as study methods and sizes. We also explored whether the type of yoga, type of cancer, exercise format (individual versus group-based yoga; supervised or unsupervised), and participant age made any difference to the results.
What did we find?
We found 21 studies involving 2041 participants with various cancers. Most were women with breast cancer. Yoga was started during anticancer therapy in 13 studies and after therapy in eight studies. We did not find any studies in which participants practised yoga before anticancer treatment.
Yoga during anticancer therapy
It is unclear if yoga during anticancer therapy has an effect on short-, medium-, or long-term cancer-related fatigue compared to no yoga.
Yoga during anticancer therapy may increase short- and medium-term quality of life compared to no yoga, but we are very uncertain about the results. None of the studies measured long-term quality of life.
We do not know if doing yoga or not during anticancer therapy leads to adverse events. Only one study reported this outcome, meaning the evidence was weak/limited.
We did not find differences in the effects of different types of yoga, group and individual training, or supervised and unsupervised training.
Yoga after anticancer therapy
Yoga after anticancer treatment probably reduces short-term cancer-related fatigue compared to no yoga. We do not know if yoga after anticancer therapy reduces medium-term cancer-related fatigue. None of the studies measured long-term cancer-related fatigue.
Yoga after anticancer therapy may increase short- and medium-term quality of life slightly, but we are very uncertain about the results. None of the studies measured long-term quality of life.
We do not know if doing yoga after anticancer therapy leads to any adverse events.
We did not find differences in the effects of different types of yoga, types of cancer, or between age groups.
What are the limitations of the evidence?
The people in the studies were aware of which treatment they were getting – yoga or no yoga. Although this is inevitable for this type of research, it could have influenced the results. For some effects (e.g. medium-term and long-term effects), we did not find studies large enough to be certain about our results. Therefore, more research is needed to understand how sustainable the effects of yoga are for cancer-related fatigue, quality of life, and adverse events.
How current is this evidence?
The evidence is current to October 2023.
Read the full abstract
Cancer-related fatigue (CRF) is one of the most prevalent symptoms in individuals with cancer. Various types of exercise have shown beneficial effects. While previous systematic reviews suggest exercise may improve CRF and quality of life, evidence specifically about yoga's impact, as well as evidence on long-term effects, is limited. Previous syntheses offer promising but inconclusive findings on yoga’s effectiveness. This review is one of a suite of five reviews exploring exercise for cancer-related fatigue.
Objectives
To assess the effects of yoga versus no yoga on cancer-related fatigue in people with cancer:
• before, during, and after anticancer treatment;
• in the short, medium, and long term;
• and effects on quality of life (QoL), adverse events, depression, and anxiety.
Search strategy
We used CENTRAL, MEDLINE, Embase, five other databases and two trials registers, together with reference checking, citation searching and contact with study authors to identify studies that are included in the review. The latest search date was October 2023.
Selection criteria
We included randomised controlled trials (RCTs) comparing yoga to no yoga. We included studies in adults (aged 18 and older) with any type of cancer and anticancer therapy who received yoga before, during, or after anticancer therapy. We included trials evaluating at least one of the main outcomes (CRF or QoL). Yoga had to last for at least five sessions, and involve face-to-face instruction. We excluded trials with fewer than 20 participants randomised per group.
Data collection and analysis
The outcomes of interest in this review are cancer-related fatigue (CRF), quality of life (QoL), adverse events, depression, and anxiety. We used standard methods expected by Cochrane. For analyses, we pooled results within the same period of outcome assessment (i.e. short, medium, and long term), and employed a random-effects model. We assessed risk of bias with the Cochrane risk of bias (RoB) 1 tool, and used GRADE to assess the certainty of the evidence.
Main results
We included 21 RCTs with 2041 people with cancer who received yoga during (13 studies) or after (eight studies) anticancer therapy; none examined yoga initiated before therapy.
Here we present results on CRF and QoL; findings on adverse events, depression, and anxiety are in the full review.
Yoga during anticancer therapy
The evidence is very uncertain about the effect of yoga compared to no yoga on: short-term CRF (standardised mean difference (SMD) 0.07, 95% confidence interval (CI) -0.18 to 0.32; mean difference (MD) on Brief Fatigue Inventory (BFI; lower values mean better outcome) of 0.16, 95% CI -0.41 to 0.71; 3 studies, 253 participants); medium-term CRF (MD on Multidimensional Fatigue Inventory (MFI; lower values mean better outcome) of -1.30, 95% CI -3.50 to 0.90; 1 study, 67 participants); and long-term CRF (MD 0.09 on BFI, 95% CI 1.16 to 0.98; 2 studies, 155 participants) (all very low-certainty evidence).
Yoga may have a small beneficial effect or no effect compared to no yoga on short-term QoL (SMD 0.25, 95% CI 0.04 to 0.45; MD on Quality of Life Questionnaire-C30 (QLQ-C30; higher values mean better outcome) of 5.28, 95% CI 0.84 to 9.56; 4 studies, 374 participants) and medium-term QoL (MD on QLQ-C30 of 7.63, 95% CI 6.71 to 21.97; 2 studies, 151 participants), but the evidence is very uncertain (all very low-certainty evidence). None of the included studies reported long-term QoL.
Yoga after anticancer therapy
Yoga probably has a beneficial effect compared to no yoga on short-term CRF (SMD -0.26, 95% CI -0.42 to -0.09; MD 2.55, 95% CI 0.88 to 4.12; higher values mean better outcome; 5 studies, 602 participants; moderate-certainty evidence). Yoga might have a beneficial effect or no effect compared to no yoga on medium-term CRF, but the evidence is very uncertain (MD 3.02, 95% CI -1.48 to 7.52; 1 study, 54 participants (higher values mean better outcome; very low-certainty evidence). None of the included studies reported long-term CRF.
Yoga may have a small beneficial effect or no effect compared to no yoga on short-term QoL (SMD 0.19, 95% CI -0.09 to 0.47; MD -3.27, 95% CI -8.08 to 1.55; higher values mean better outcome; 4 studies, 275 participants) and medium term QoL (MD 7.06, 95% CI -1.38 to 15.50; 1 study, 54 participants; higher values mean better outcome), but the evidence is very uncertain (all very low-certainty evidence). None of the included studies reported long-term QoL.
A key limitation of the review was the included studies' methodological constraints: participants' awareness of treatment assignments (yoga or control) potentially introduced bias. Additionally, sample sizes were too small to determine medium- and long-term effects conclusively. Further research is needed to evaluate the sustainability of yoga's impact on cancer-related fatigue, quality of life, and adverse events.
Authors' conclusions
Our review provides uncertain evidence of the beneficial effects of yoga initiated during or after anticancer therapy compared to no yoga for people with cancer. Although there are indications supporting the use of yoga to address CRF, the uncertainty of the evidence underscores the need for caution in its implementation. Future RCTs should employ rigorous methodologies, enrol sufficient participants, and use appropriate controls.
