Results show that an effective psychological intervention—one achieving significant changes in psychological and immune measures—can also improve health. In this study health was defined both with global ratings of the patient’s performance status and specific ratings of common signs and symptoms of medical conditions and illnesses, laboratory studies, and possible toxicities from chemotherapy and radiation therapy regimens. Path analyses were used and the model explained 36% of the variance in health at 12 months. The intervention had both a direct effect and an indirect effect; by specifically lowering the patients’ levels of emotional distress, the health outcomes were more positive. Although the intervention was also associated with positive immune responses, these changes were unrelated to subsequent changes in health status.
The higher functional status and lower level of symptomatology, toxicities, etc. for the intervention group is clinically important. Characteristics of the present trial—disease endpoints as primary outcomes and tests of mechanisms for an effect—made it important to have longitudinal documentation of the patients’ general health. Search measures in several literatures were unproductive or unsatisfactory. Thus, we turned to the cancer treatment clinical trial studies for solutions. Because of the predominance of ongoing SWOG clinical trials at our institution at the time, their listing was chosen, as many of our patients would be participating in trials for which this listing was designed. Indeed, after disease markers, these data become the secondary endpoints in Phase III trials. When treatments are compared and found to be equally efficacious, these data become, for many patients and physicians alike, the basis for choosing among treatments (see Potosky et al., 1999
for data for prostate cancer; see discussion in Goodwin, et al., 2003
, for breast cancer). In addition, these health data provide guidance for dosage modification in Phase II trials (Pelegri et al., 2005
The health measures in this study also have importance as they covary with behavioral and psychological variables. The magnitude of treatment toxicities has been used to determine risk for poor adherence to treatment (Ayres et al., 1994
; Levin et al., 1999
; Demissie et al., 2001
). Knowing the extent of a slowed recovery and/or disease and treatment morbidities is important for caring for survivors. Poor health status has a negative effect on mood (Ganz et al., 2004
) and quality of life (Ganz et al., 2004
; Levin et al., 1999
), and health worries are the source of greatest concern among survivors (Spencer et al., 1999
), as poor health negatively impacts personal relationships (Wimberly et al., 2005
), daily activity levels, and return to normal routines such as employment (Bradley et al., 2005
). In addition, poorer health impacts the meaning patients derive from life following cancer (Jim & Andersen, in press
While some psychological trials have used the KPS (Dodd, 1988
; Northouse et al., 2005
; Scheier et al., 2005
) the use of an extensive symptomatology and toxicity listing is novel. These measures are costly, as a high level of rater expertise is required (e.g., a nurse specialist), and they are time consuming with the patient interview, evaluating lab results and chart data, etc. Yet, they provide significant breadth, relevance, and with symptom-specific graded scales, objectivity. These measures are different in content and method from self-reported perceptions of health or symptoms. Correlations between patients’ reports of emotional distress and evaluations of their physical health may be inflated from shared method variance (i.e., both self-report measures). In addition to the objectivity of the items used here, nurses blinded to the patients’ study arm assignment were the raters. These factors greatly reduce measurement error related to the patient (e.g., reporting bias).
A second aim of this report was to identify how
this psychological intervention could achieve positive health effects. While there are many possible routes, two likely mechanisms were tested. The path model accounted for the contribution of distress reduction, per se, on health status. In addition, the direct effect of the intervention suggested that additional mechanisms also played a positive role. The intervention included multiple components, and we can only speculate about which factors may be influential. Progressive muscle relaxation (PMR) provided patients with an active, and portable, means to reduce daily stress and cope with and control symptoms (e.g., nausea, disturbed sleep, fatigue). In other studies with cancer patients, PMR has yielded reductions in anxiety (Lyles et al., 1982
) and elevations in immune measures (Lekander et al., 1997
). Other intervention components also may have had general health benefits also; possibilities include recommendations for regular exercise [which has had symptom reducing effects in other studies with breast cancer patients (e.g., MacVicar et al., 1989
)] and teaching patients to use direct, assertive communications with their physicians and nurses to get their medical needs met. Future studies will explore these and other possibilities.
There is great research interest in the potential for interrelationships among stress, immunity, and health (Kiecolt-Glaser et al., 2002
). It is suggested that a robust immune response might maintain health by lowering one’s risk for infection or illness (Janeway, 2004
), for example. While there is correlational evidence for the covariation of heightened stress, lowered immunity, and selected health outcomes (Kiecolt-Glaser et al., 2002
), there are few experimental data in which stress is ‘manipulated’ (via randomization to an intervention) and the consequent effect on immunity and health are tested. To our knowledge, only Fawzy et al. (1993)
provided relevant data, though not a test of relationships among the three variables. They reported that lower
levels of baseline distress predicted recurrence and death, and higher natural killer cell activity predicted a lower risk for recurrence, though not survival.
In the present study, the intervention-produced changes in blastogenesis levels were statistically significant, but did not relate to health measures. [We also note that the effect size for the PHA observed at 12 months was ‘medium’ to ‘large’ by accepted standards (Cohen, 1988
) and compares favorably with other estimates. In a meta analysis of psychological interventions and immunity, effect sizes for blastogenesis measures were small (rs
of −.05 for ConA and .13 for PHA (Miller and Cohen, 2001
)]. However, our health outcome assessed many bodily systems, a few of which likely had more direct relevance to immunity (‘infection’) than several of the others. Studying a health outcome particularly relevant for T-cell function and selection of assays with a direct link to a specific health outcome (Lutgendorf et al., 2002
), may provide additional information regarding this hypothesized mechanism.
In summary, results show that a psychological intervention yielding robust biobehavioral effects also improved health. This was achieved, in part, through lowering of emotional distress rather than the seemingly positive effect that the intervention had on T-cell immunity. Ten-year follow-up are being collected to determine whether health status of these patients is related to disease progression, as the survivorship period brings new challenges for cancer patients (Yabroff et al., 2004