This article is part of our October 2020 special issue. Download the full issue here.
Oberoi S, Yang J, Woodgate RL, et al. Association of mindfulness-based interventions with anxiety severity in adults with cancer: a systematic review and meta-analysis. JAMA Netw Open. 2020;3(8):e2012598.
The aim of this review was to determine whether mindfulness-based interventions (MBIs) improve anxiety in cancer patients.
The researchers conducted a systematic review and meta-analysis of clinical trials “extracted from MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL, PsycINFO, and SCOPUS from database inception to May 2019.”
All trials were randomized to MBI versus a control group, which could be a sham treatment, no intervention, waitlisted participants, or usual care. Inclusion criteria included adults and children with cancer or who were receiving stem cell treatment for cancer.
Exclusion criteria included “observational, quasi-randomized, crossover, or cluster-randomized trial designs and trials that did not report any outcomes of interest to this review.” There were no languages excluded from the data extraction. Interventions that included physical movement, such as yoga, qigong, and tai chi, were excluded.
The 28 studies included in the meta-analysis involved a total of 3,053 individuals. All participants were adults, since none of the trials with subjects aged less than 18 years met review criteria. Participants could be in active treatment or posttreatment, with some receiving MBIs both during and after their treatments.
An initial search found 5,686 citations. After blinded screening and independent review by 2 of this publication’s authors, 27 trials ultimately met the review criteria. The researchers added another study, which they found by hand, for a total of 28 trials.
Primary Outcome Measures
The primary outcome measure was the severity of short-term anxiety up to 1 month post MBI. Secondary outcome measures included anxiety, depression, and quality of life in the medium term (1–6 months) and long term (6–12 months) after MBI.
The most common MBI used in the trials included mindfulness-based stress reduction (MBSR; 13 trials, 46.4%) and mindfulness-based cognitive therapy (MBCT; 6 trials, 21.4%). The median duration of MBIs was 8 weeks. There were 12 different anxiety scales used in the trials, with Hospital Anxiety and Depression Scale A (HADS-A; 5 trials) and State-Trait Anxiety Inventory (STAI; 5 trials) being the most common. Breast cancer was by far the most well-represented cancer type in this review. Twelve trials (42.8%) looked at MBIs and breast cancer exclusively. Eleven recruited participants with various cancer types, and of these, breast cancer was still the most prevalent cancer in 10 of the studies.
MBIs significantly reduced short-term (0–1 month) anxiety (23 trials; 2,339 participants; SMD, −0.51; 95% CI, −0.70 to −0.33; I2=76%). Reduction in short-term anxiety was evident when HADS-A or the STAI scale was used in independent statistical analysis of each.
MBIs also reduced the severity of medium-term (>1–6 months) anxiety (9 trials; 965 participants; SMD, −0.43; 95% CI, −0.68 to −0.18; I2=66%).
MBIs were not associated with long-term (>6 months–1 year) reduction in anxiety (2 trials; 403 participants; SMD, −0.02; 95% CI, −0.38 to 0.34; I2= 68%).
Additional findings demonstrated a reduction in depression in the short term (19 trials; 1,874 participants; SMD, −0.73; 95% CI, −1.00 to −0.46; I2=86%) and medium term (8 trials; 891 participants; SMD, −0.85; 95% CI, −1.35 to −0.35; I2= 91%), but not in the long term (2 trials; 349 participants; SMD, −0.96; 95% CI, −2.38 to 0.46; I2= 97%).
MBIs were also associated with improvement in overall health-related quality-of-life (HRQOL) scores in both the short term (9 trials; 1,108 participants; SMD, 0.51; 95% CI, 0.20 to 0.82; I2=82%) and medium term (5 trials; 771 participants; SMD, 0.29; 95% CI, 0.06 to 0.52; I2=57%) The single trial that tracked HRQOL long term did not show any benefit (1 trial; 153 participants; WMD, 0.78; 95% CI, −5.98 to 7.54).
Mindfulness is a concept dating back thousands of years to ancient Eastern philosophy and is commonly linked to the Buddhist tradition. Jon Kabat-Zinn, PhD, one of the pioneers of the modern mindfulness movement, describes mindfulness as “the awareness that emerges through paying attention on purpose, in the present moment, and nonjudgmentally to the unfolding of experience moment by moment.”1 Kabat-Zinn was one of the first individuals to study mindfulness in the context of health and well-being. After graduating from the Massachusetts Institute of Technology (MIT), he started a stress-reduction clinic at the University of Massachusetts Medical School. In 1979, he created Mindfulness-Based Stress Reduction (MBSR), an 8-week group course. The program teaches mindfulness as a meditation practice, but also as a way of life.2 He then began researching the role of mindfulness in chronic pain and immunity. Kabat-Zinn studied the MBSR program’s effects in breast and prostate cancer patients, the first research of its kind.
While thousands of studies on mindfulness in cancer patients have been performed, most demonstrate only moderate improvement. For example, when compared to exercise, mindfulness was no more capable of producing the desired result.
Several studies have found mindfulness to benefit cancer patients. A systematic review conducted in 2019 by Ngamkham, Holden, and Smith found mindfulness interventions may decrease cancer-related pain and improve quality of life.3 A 2014 Canadian study confirmed the findings of the Nobel laureate and discoverer of the enzyme telomerase, Elizabeth Blackburn, namely that mindfulness interventions indeed affect telomere length.4 In the Canadian study, breast cancer survivors who participated in a mindfulness-based cancer recovery (MBCR) program or group therapy maintained telomere length, whereas those who did not participate in any program had telomere shortening, a sign of cellular aging.5
The study currently under review is a meta-analysis providing some evidence that MBIs reduce anxiety in cancer patients and is a valuable contribution due to the larger number of subjects (N=3,053), as well as the inclusion of any type cancer. Other reviews have been done. A 2017 meta-analysis of 1,709 breast cancer patients looked at how MBSR/MBCT had significant effects on quality of life, fatigue, sleep, stress, anxiety, and depression.6 Another meta-analysis from 2015 confirmed the effectiveness of MBIs on reducing anxiety and depression.7
Despite the amount of evidence we now have regarding the therapeutic effects of mindfulness, critics of mindfulness still exist. While thousands of studies on mindfulness in cancer patients have been performed, most demonstrate only moderate improvement. For example, when compared to exercise, mindfulness was no more capable of producing the desired result.8 The research on mindfulness has been criticized for many reasons. Some include studies having small sample sizes, lack of diversity in patients, and lack of diversity in types of cancers. Many of the study designs also lack randomized controls, as well as long-term follow-up.9
Nevertheless, a great number of oncology centers offer mindfulness, most commonly in the form of MBSR or MBCT. The programs are usually 8 weeks long, with a weekly group session covering different aspects of mindfulness and daily individual exercises to be performed at home. Common techniques include non-judging, patience, kindness, and acceptance.10
Decades of research provide an argument for the use of mindfulness in patients with cancer, but more research is needed for broad adoption of its use. While the academic debate over the efficacy of MBIs goes on, few will disagree that decreasing anxiety and depression and improving quality of life can alter a patient’s life for the better.