Yoga improves the quality of life of women undergoing radiotherapy for breast cancer more than the use of simple stretching exercises alone, according to a study published online in the Journal of Clinical Oncology. It also appears to control patients' cortisol levels, which can lead to better outcomes.
Lorenzo Cohen, PhD, from the integrative medicine program at MD Anderson Cancer Center, and colleagues performed the study as part of an ongoing effort to scientifically validate mind-body interventions in cancer patients. It was conducted in collaboration with India's largest yoga research institution, Vivekananda Yoga Anusandhana Samsthana (VYASA) in Bangalore (JCO, March 3, 2014).
"By comparing women doing yoga to women doing stretching exercises, we see that the benefits of yoga go beyond just its physical aspects," Cohen told AuntMinnie.com. "We know that exercise in the form of stretching does help with fatigue and a little with physical functioning, but the benefits of yoga are apparent above and beyond stretching."
Research on yoga in patients with cancer has increased in the past decade, with studies reporting improvements in patients' stress levels, fatigue, emotional health, pain, and sleep disturbances, the authors wrote. But previous research has been hindered by an absence of objective criteria to measure yoga's effect. That's why Cohen's group also measured study participants' cortisol rhythm in the study. Higher stress hormone levels throughout the day -- known as a blunted circadian cortisol rhythm -- have been linked with worse outcomes in breast cancer.
The study included 163 women with stage 0 to stage III breast cancer. The women were invited to participate in the study before starting radiotherapy, and they were randomly assigned to a yoga protocol (53 patients), a stretching protocol (56 patients), or a control group (54 patients). The women completed surveys to measure quality of life, fatigue, depression, and sleep quality at the beginning and end of the six-week period; the participants also had five saliva samples collected per day for three consecutive days at the beginning of the study, the end of treatment, and one, three, and six months later.
The yoga and stretching classes, held near the radiation treatment center, consisted of 60-minute sessions three times per week, throughout six weeks of radiotherapy. The yoga program included a preparatory warm-up, performing selected postures, deep relaxation, alternate-nostril breathing, and meditation, and was taught by VYASA-trained teachers. The stretching program included standing, lying down, and sitting positions that approximated the yoga program movements, but there were no relaxation or meditation exercises. It was taught by physiotherapists from MD Anderson's rehabilitative and physical therapy department.
"Women in the yoga and stretching groups were also encouraged to practice daily on the days they did not have sessions at the hospital," Cohen told AuntMinnie.com.
Women in the control group were given usual care, completed survey and saliva collection assessments on the same timeline as the other groups, and were offered yoga or stretching classes at the end of the study period. All participants were asked to avoid other yoga classes during the study time frame.
The yoga group had significantly greater increases in physical functioning scores than the control group at one and three months after radiotherapy. At one, three, and six months, the yoga group had greater increases in physical functioning than both the stretching and control groups. By the end of radiotherapy, the yoga and stretching groups also showed a reduction in fatigue, Cohen's group wrote. There were no group differences for mental health and sleep quality.
One of the most exciting findings was that the cortisol slope was steepest for the yoga group, compared with the stretching and control groups, at the end of radiotherapy and one month after, according to Cohen.
"Cortisol is a stress hormone that follows a diurnal cycle: high in the morning when we wake up and dropping throughout the day before reaching the lowest point before bed," he told AuntMinnie.com. "Research with breast and kidney cancer patients has shown that a less steep slope with levels not dropping by the end of the day leads to shorter survival -- which suggests that maintaining healthy regulation of cortisol may improve outcomes in cancer patients."
Following this research, the group plans to conduct a phase III clinical trial with 600 women with breast cancer who are undergoing radiotherapy. The trial will further explore the mechanisms of yoga that lead to improvements in physical functioning, quality of life, and biological outcomes during and after radiation treatment. Its secondary aim will be to assess the cost-efficiency of mind-body programs for the hospital, healthcare use costs in general, and patients' work productivity. The trial is supported by a grant from the National Cancer Institute.
"In terms of changing U.S. healthcare policy for the treatment of breast cancer patients undergoing radiotherapy and insurance reimbursement, we need to wait on the findings from the phase III study," Cohen told AuntMinnie.com. "In terms of what we should recommend to our patients and have them do to improve their outcomes during cancer treatment -- all cancer patients should engage in some type of mind-body practice during and after treatment."