Biological Outcomes

We have also become interested in the effects of MBSR on some of the biological processes identified by researchers as affected by cancer treatments, which may have potential consequences in terms of future health and disease recurrence. In the study described above with breast and prostate survivors an average of 1.1 years post-treatment, we investigated immune function by looking at the counts of a number of lymphocyte subsets, including T cells (divided into helper and cytotoxic T cells) and NK cells. In addition to counting cells, we also tested their function by measuring how much of four different cytokines were secreted by the T and NK cells in response to an immune challenge. Cytokines were either of the pro-inflammatory or anti-inflammatory variety—pro-inflammatory processes have been associated with several poorer outcomes in both cardiovascular and cancer patients.100,113 Although there were no significant changes in the overall number of lymphocytes or cell subsets, T-cell production of interleukin (IL)-4 increased and interferon gamma (IFN-X) decreased, whereas NK cell production of IL-10 decreased. These results are consistent with a shift in immune profile from one associated with depressive symptoms to a more normal profile. We also assessed the patterns of change over a full year following program participation. Although complicated, the pattern of change in cytokines over 1 year of follow-up supported a continued reduction in pro-inflammatory cytokines.114

We also looked at salivary cortisol levels, since daily salivary cortisol levels have been related to stress and health, and are often dysregulated in cancer survivors; such dysregulation has been associated with poorer disease outcomes. We assessed salivary cortisol three times daily both before and after program participation, and looked at the shape of the pattern of cortisol secretion throughout the day—abnormal profiles have been associated with shorter survival in metastatic breast cancer patients.115 Interestingly, these hormone profiles also shifted pre- to post-intervention in our participants, with fewer evening cortisol elevations found post-MBSR and some normalization of abnormal diurnal salivary cortisol profiles occurring.104 The clinical significance of this finding has yet to be pursed. We then followed these same participants for a full year, and found continuing decreases in overall cortisol levels over 6 and 12 months of follow-up, mostly due to decreases in evening cortisol levels.114 This is significant as higher cortisol levels, particularly in the evening, are considered to be an indicator of dysregulated cortisol secretion patters and poorer clinical outcomes.

Measures of autonomic system function have also been of interest, since cancer survivors are at high risk for cardiovascular disease. Hence, we looked at the effects of MBSR on resting blood pressure and heart rate. In a group of breast and prostate cancer survivors, overall resting systolic blood pressure (SBP) decreased significantly from pre- to post-MBSR.114 Correlations were significant between resting HR and mood disturbance scores at pre-intervention, and between HR and the total stress scores at pre-intervention, and 6- and 12-month follow-ups. This indicates that elevated resting HR was related to the experience of more symptoms of mood disturbance of stress. Consistently, elevated HR is also a risk factor for cardiovascular disease.

In other work with biological outcomes, an innovative study by Kabat-Zinn's group looked at the effects of combining a dietary intervention with MBSR on prostate specific antigen (PSA) levels, an indicator of the level of activity of the prostate cancer, in men with biochemically recurrent prostate cancer.116 They found the combined program resulted in a slowing of the rate of PSA increase in a pilot sample of 10 men, and are currently conducting a larger RCT to verify this significant impact on such an important marker of biochemical recurrence in prostate cancer.

Taken together, these studies begin to hint at the potential for psychosocial interventions, specifically MBSR, to impact biological mechanisms that may be important for future health outcomes. This research area is in its infancy and many opportunities for innovative research exist.

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