This review investigated whether mind-body therapies are effective for relieving cancer-related pain in adults, since at least one-third of adults with cancer are affected by moderate or severe pain.
The authors searched for all randomized or quasi-randomized controlled trials that included adults (≥18 years) with cancer-related pain who were treated with:
- guided imagery,
- progressive muscle relaxation.
The primary outcome was pain intensity.
A total of 40 primary studies involving 3569 participants were found. The meta-analysis included 24 studies (2404 participants) and showed a significant effect of -0.39 (95% CI -0.62 to -0.16) with considerable heterogeneity (I2 = 86.3%, p < 0.001). After excluding four “outlier” studies in sensitivity analyses, the effect size remained significant but became weaker. There was a high risk of bias in all studies, for example, performance bias due to lack of participant blinding. Patients in multiple settings were included but many studies were of low quality.
The authors concluded that mind-body therapies may be effective in improving cancer pain, but the quality of the evidence is low. There is a need for further high-quality clinical trials.
These conclusions are broadly correct. I can confirm this because I recently summarized the evidence in a book and arrived at very similar conclusions. If I had to criticize the review, it would be for not including all mind-body therapies for which there is evidence from clinical trials. In my book, I was able to include the following additional treatments:
- Autogenic training
- Music therapy
- Tai chi
The effects of these treatments are about the same regardless of which one we use. This might lead us to suspect that they work not via specific but via non-specific effects, e.g. placebo.