RESUMEN
BACKGROUND: : Previous studies of cancer patients investigated the effect of psychological treatment on basal endocrine and immune values. Using a randomized experiment, we explored the effect of a 13-week experiential-existential group psychotherapy (EEGP) program on the reactivity to a speech task in breast cancer patients. We explored whether changes in cardiovascular and immune reactivity to a speech task over the 3-month period correlated with changes in psychological distress and emotional expression. METHODS: Patients who had been treated for early-stage breast cancer and who were diagnosed as having either positive axillary lymph nodes or distant metastases were randomly assigned to either EEGP or a waiting list control (WLC) condition. We continuously recorded heart rate (HR), diastolic (DBP) and systolic blood pressure (SBP) in response to the speech task before and after treatment. We also measured lymphocyte proliferation to pokeweed (PWM) and phytohemagglutinin (PHA), and natural killer cell activity (NKCA) as well as peripheral blood lymphocyte distributions in blood samples that were drawn before, during and after the speech task. RESULTS: Patients in EEGP had smaller increases in natural killer (NK) cells induced by the speech task after treatment versus task-induced values observed at study entry and greater than pre-/posttreatment changes seen in patients randomized to the WLC. A similar pattern emerged with respect to NKCA over the intervention period, which was independent of the changes in NK cells. There were no differences between patients assigned to EEGP and WLC in HR, DBP and SBP responses as well as in changes in PWM- and PHA-induced lymphocyte proliferation in response to the speech task measured before and after the 3-month intervention period. Individual differences in pre-/posttreatment increases in emotional expression but not in psychological distress were significantly associated with smaller changes in the number and function of NK cells over the 3-month period. CONCLUSIONS: These findings may indicate that emotional expression during EEGP may render breast cancer patients more comfortable expressing their emotional responses to the speech challenge, which, in turn, results in smaller stress-induced changes in NK cells and function.
