(San Antonio, Texas) — The practice of yoga might reduce psychological distress and modulate abnormal cortisol levels and immune responses in patients with metastatic breast cancer, according to a study presented here at the 34th Annual San Antonio Breast Cancer Symposium.
This suggestion comes from a small randomized trial conducted collaboratively by yogis and medical doctors, including S.K. Gopinath, MD, from the Department of Surgical, Medical and Radiation Oncology at the HCG-BIO Super Specialty Center in Bangalore, Karnataka, India.
In a 3-month study, 45 patients were randomized to a daily yoga intervention and 46 to standard supportive counseling. The subjects, with an average age of 50.5 years, were assessed at baseline and after the intervention.
The yoga intervention was resoundingly effective in improving psychosocial states.
After the intervention, there was a statistically significant decrease in anxiety (P <.001), depression (P < .001), perceived stress (P = .01), fatigue severity (P < .001), and fatigue interference (P < .001) in the yoga group, compared with the control group. There was also a significant improvement in emotional function (P < .001), role function (P = .03), cognitive function (P < .001), and global quality of life (P < .001) in yoga group.
The researchers also evaluated biologic measures. At the beginning and the end of the intervention, daily saliva samples were collected at 9:00 am and 10:00 pm, and enzyme immune assay kits (Salimetrics) were used to evaluate cortisol levels. In addition, blood samples were collected for 3 consecutive days between 8:00 am and 10:00 am so that natural killer cells could be enumerated with flow cytometry.
Again, yoga was uniformly effective. There was a significant decrease in the yoga group in early morning (6:00 am) cortisol levels (P = .03).
This finding means that cortisol, which is a measure of stress and naturally decreases when the body is at rest, was successfully modulated in the yoga group. Research has shown that patients with metastatic breast cancer whose diurnal cortisol rhythms were flattened or abnormal have earlier mortality (J Natl Cancer Inst. 2000;92:994-1000).
After the intervention, there was also a significant increase in the percentage of natural killer cells in the yoga group (P = .03), compared with the control group. Previous research has demonstrated that natural killer cells, which are naturally occurring cytotoxins, play a therapeutic role in the treatment of human cancers (Cancer. 1996;77:1226-1243).
More Study Details
Overall, yoga might improve quality of life, say the researchers, who included staff from the Department of Yogic Sciences at the Swami Vivekananda Yoga Anusandhana Samsthana University, in Bangalore.
Staff at the university have authored more than 150 scientific papers on yoga and disease, according to the institution’s Web site.
The researchers used a number of common instruments to measure psychosocial outcomes: mood states (a hospital anxiety and depression scale), sleep quality (the Pittsburgh Insomnia Rating Scale), quality of life (the EORTC Core Quality of Life Questionnaire for breast cancer [QLQ-C30]), and perceived stress (a perceived stress scale).
They describe the rigor of their quantitative work. The data were analyzed using both parametric (analysis of covariance, with a respective baseline measure as a covariate) and nonparametric (the Mann–Whitney U test) tests to evaluate the effects of intervention on the outcome measures. Also, data for salivary cortisol were log transformed, and area under the curve and cortisol slope were computed using a linear mixed-effects model.
The study participants were likely under great duress, Dr. Gopinath and colleagues explain. “Metastatic breast cancer patients experience tremendous psychological distress due to treatment, disease, and uncertainty of their survival,” they write in their abstract.