Effects of Qigong Therapy on Alleviating Symptoms in Cancer Patients: An Overview
5.4 Discussion
5.4.1 Appraisals of Included SRs
Our search indicated that the interest in Qigong for cancer care is growing. The results of this overview suggest that the evidence regarding the ef fi cacy of Qigong in cancer treatment is not conclusive. More than 50% of the primary studies included in the SRs were not randomized and thus open to selection bias, which may be the primary reason for the inconsistency in the conclusions of the SRs.
Moreover, the inconsistencies in the primary studies may also be due to different Qigong regimens. In some trials, the dose of Qigong may have been too small to
generate a signi fi cant effect. In addition, most primary studies employed different forms of Qigong interventions. There are signi fi cant differences between the vari- ous forms of Qigong, which poses dif fi culties in establishing quality standards of treatment. Some types of Qigong applied in the study protocols may not have been suitable for cancer care. This issue should be addressed in future studies comparing the ef fi cacy of the various forms of Qigong. This will require more precise descrip- tions of the Qigong interventions used in the study and a description of the level of expertise of the instructors.
5.4.2 Adverse Events of Qigong
Qigong appears to be generally safe, and serious adverse effects have not been reported. Some studies have noted adverse events, including headache, dizziness, nausea, mental disorders and psychosis, in individuals who practiced Qigong incor- rectly, although these risks have not been formally studied (Ng 1999 ; Lee 2000 ; Kemp 2004 ) . Adverse effects were not the focus of this review; regardless, the safety of Qigong needs further research.
5.4.3 Possible Mechanisms of Qigong
Most studies have reported a positive effect of Qigong on the physiological level, although the effects of Qigong on the symptoms of cancer treatment were not consis- tent. One possible mechanism by which Qigong may improve immune function is the modulation of cytokine and hormone levels, which may counteract the immune de fi ciency experienced by most cancer patients (Jones 2001 ; Chen 2004 ) . Others have postulated that Qigong improves micro-circulatory functions, including changes in blood viscosity, the elasticity of blood vessels, and platelet functions (Chen 2004 ) . A third proposed mechanism is an increase in the pain threshold as a result of the relaxation effects (Chen 2004 ) . It is also possible that Qigong induces apoptosis in pancreatic cancer cells and increases or represses PI3K activity in highly enriched PI3K preparations, suggesting that external Qigong could positively or negatively regulate enzymes (such as Akt and Erk1/2) in different settings (e.g. in cancer cells vs normal cells) (Yan et al. 2006, 2008 ) . If these theories are con fi rmed, they may explain how Qigong leads to clinical improvements in patients.
5.4.4 Possible Interpretation
The fact that there is no good trial evidence in support of Qigong therapy for cancer care is in line with several different interpretations. Qigong may be ineffective, the studies may have been incorrectly designed or the treatment may not have been administered
optimally in the existing studies. For instance, the number of Qigong sessions could have been too small to generate a signi fi cant effect, or the type of Qigong or the applied protocol might not have been suitable for cancer care. A clinical study is only truly use- ful if the intervention used can be replicated, and hence, the type of Qigong employed and a full description are important. There are signi fi cant differences between the numer- ous forms of Qigong, which pose dif fi culties in establishing quality standards of treat- ment. A clear description of the Qigong intervention used should be provided together with a description of the level of expertise of the instructors.
5.4.5 Recent RCTs
Further, two RCTs, that tested effects of ten weeks of 90 min Qigong on QoL in cancer patients, were recently published (Oh et al. 2010, 2012b ) . A two-armed RCT conducted by the University of Sydney assessed the effectiveness of Qigong on QoL, fatigue, mood, and in fl ammation in various cancer patients compared with usual care control and showed favorable effects of Qigong for improving QoL and mood, and reducing speci fi c side effects of conventional cancer treatment (Oh et al. 2010 ) . Another recent RCT conducted by the same group investigates the effectiveness of Qigong on cognitive function, QoL, and biomarker of in fl ammation in various can- cer patients compared with usual care (Oh et al. 2012b ) . The results showed bene fi cial effects of Qigong on cognitive function and QoL. These two RCTs showed favorable effects of Qigong on symptoms of cancer. However, results of the largest trial (Oh et al. 2010 ) already included in recent SR (Chan et al. 2012 ) . Even though the latest study (Oh et al. 2012b ) is included and overall evidence is still inconclusive.
5.4.6 Limitations of This Overview
Our overview has several limitations. Although our search strategy seemed thor- ough, we cannot totally exclude the possibility that relevant articles were missed. It is also possible that evaluating SRs rather than clinical trials may not capture the relevant details of the primary studies. Furthermore, the fact that the SRs were con- ducted on primary data of poor quality is a major limitation of this study. Collectively, these drawbacks render our verdict about Qigong less robust than we had hoped.
5.4.7 Perspectives
This overview of SRs focused on the effects of Qigong as supportive cancer care.
Collectively, the existing trial evidence is not convincing and does not show Qigong to be an effective modality for supportive cancer care.
Our overview may serve as a stimulus for future Qigong research to become more rigorous. We recommend that researchers study the CONSORT guidelines (Schulz et al. 2010 ) and that authors of SRs examine the PRISMA guidelines to achieve this goal (PRISMA 2009 ) .
Future RCTs of Qigong for supportive cancer care should adhere to accepted standards of trial methodology. The studies published up to date showed a number of problems that have been noted by other reviews of trials examining the ef fi cacy of Qigong, e.g. expertise of Qigong practitioners, the pluralism of Qigong, fre- quency and duration of treatment, employing validated primary outcome measures and adequate statistical tests, and heterogeneous comparison groups (Chen and Yeung 2002 ; Wayne and Kaptchuk 2008 ) . Future studies should be of high quality with a particular emphasis on designing adequate and appropriate control groups.