A new US study finds that yoga can benefit breast cancer survivors by reducing fatigue and inflammation. While yoga has many components, the researchers believe breathing and meditation probably had the biggest impact.
At the end of 12 weeks of yoga classes, a group of women who had completed breast cancer treatment, including surgery and radiotherapy, showed an average reduction in fatigue of 57% and up to 20% reduction in inflammation, compared with a similar group that had not received yoga instruction.
The researchers also found the more yoga the women practiced, the better the results.
They report the findings of the randomized controlled trial in the Journal of Clinical Oncology.
Study leader Janice Kiecolt-Glaser, a professor of psychiatry and psychology at The Ohio State University in Columbus, says the study shows how several months of modest yoga practice can benefit breast cancer survivors substantially. She also thinks the results could apply to other people who have problems with fatigue and inflammation.
Largest known trial of yoga in cancer survivors using biological measures
Many studies have shown that yoga can benefit cancer patients. For instance, in 2010, another group from the US reported how 4 weeks of yoga reduced fatigue and improved sleep quality in cancer survivors who also reported taking less sleep medication and improved quality of life.
However, the researchers behind this new study believe it is the largest known randomized controlled trial of the effect of yoga on cancer survivors that includes biological measures. They decided to concentrate on breast cancer survivors because the treatment they undergo is very rigorous and taxing, as Prof. Kiecolt-Glaser explains:
"One of the problems they face is a real reduction in cardiorespiratory fitness. The treatment is so debilitating and they are so tired, and the less you do physically, the less you're able to do. It's a downward spiral."
For the study, the researchers recruited 200 women who had undergone treatment for breast cancer and randomly assigned them to either the intervention group or a control group.
The participants were aged from 27 to 76 and had completed their surgery or radiotherapy between 2 months and 3 years before taking part in the trial: none had done yoga before they took part in the study.
Trial designed so results apply to other cancer survivors
They deliberately recruited a mix of participants with a wide age range, with cancer at various stages (from 0 to 3A), and who underwent a range of treatments, so they could generalize the results to a broad population of cancer survivors.
The intervention group received 12 weeks of twice-weekly 90-minute group classes in Hatha yoga, and was also encouraged to practice at home. The participants also kept a log of their total weekly practice.
The control group participants were wait-listed to have the same yoga classes after the study was completed and were asked not to do yoga in the meantime.
Two types of results were recorded at three points in the study period, once at the beginning, then at the end of the 12 weeks of yoga classes, and then again 3 months after that.
At all three points, both groups completed questionnaires that enabled the researchers to assess fatigue, energy levels, symptoms of depression, quality of sleep, diet and exercise.
They also gave blood samples from which the researchers could measure levels of three inflammation-related proteins: interleukin-6 (IL-6), interleukin-1 beta (IL-1B) and tumor necrosis factor-alpha (TNF-a). The participants were first injected with a compound that provoked an immune response before giving the blood samples.
Reduced fatigue, increased vitality and reduced inflammation markers
The results showed that immediately after the yoga classes ceased, the yoga group reported on average a 41% reduction in symptoms of fatigue, and a 12% higher score on vitality, compared with the non-yoga controls.
Also at this point, the yoga group showed on average lower levels of the inflammation-related proteins than the controls: 10% lower level of TNF-a, 11% lower IL-6, and 15% lower IL-1B.
Further analysis showed the yoga group experienced significantly improved sleep, compared with the control group.
This also showed the more yoga the women practiced, the bigger the improvements in fatigue, vitality, depressive symptoms, accompanied by increased reductions in two of the inflammation-related proteins.
Prof. Kiecolt-Glaser says:
"We were really surprised by the data because some more recent studies on exercise have suggested that exercise interventions may not necessarily lower inflammation unless people are substantially overweight or have metabolic problems. In this group, the women didn't lose weight, but we saw really marked reductions in inflammation. So this was a particularly striking finding biologically."
A number of health problems are linked to chronic inflammation, including type 2 diabetes, coronary heart disease, and Alzheimer's disease. Studies have also tied it to age-related frailty and functional decline.
Later, at the 6-month measuring point, 3 months after the yoga classes finished, the benefits appear to have continued to improve: fatigue was 57% lower, and inflammation was between 13% and 20% lower in the yoga group, compared with the non-yoga group.
There are many aspects to yoga, including meditation, breathing, stretching and strengthening. But the researchers think for this study, the parts that produced the most benefits were the breathing and meditation practice, as Prof. Kiecolt-Glaser explains:
"We think improved sleep could be part of the mechanism of what we were seeing. When women were sleeping better, inflammation could have been lowered by that. Reducing fatigue enables women to engage in other activities over time. So yoga may have offered a variety of benefits in addition to the yoga exercises themselves."
Funds from the National Cancer Institute helped finance the study.