A clinical trial was designed to test the hypothesis that a psychological intervention could reduce the risk for cancer recurrence. Newly diagnosed regional breast cancer patients (n=227) were randomized to Intervention with assessment or Assessment only arms. The intervention had positive psychological, social, immune, and health benefits, and after a median of 11 years the Intervention arm was found to have reduced risk of recurrence [hazard ratio (HR), 0.55; P=0.034]. In follow-up, we hypothesized that the Intervention arm might also show longer survival after recurrence. If observed, we then would examine potential biobehavioral mechanisms.
All patients were followed; 62 recurred. Survival analyses included all 62. Upon recurrence diagnosis, those available for further biobehavioral study were accrued (n=41, 23 Intervention and 18 Assessment). For those 41, psychological, social, adherence, health, and immune (natural killer cell cytotoxicity; T-cell proliferation) data were collected at recurrence diagnosis and 4, 8, and 12 months later.
Intent-to-treat analysis revealed reduced risk of death following recurrence for the Intervention arm (HR, 0.41; P=0.014). Mixed-effects follow-up analyses with biobehavioral data showed that all patients responded with significant psychological distress at recurrence diagnosis, but thereafter only the Intervention arm improved (P values<0.023). Immune indices were significantly higher for the Intervention arm at 12 months (P values<0.017).
Hazards analyses augment previous findings in showing improved survival for the Intervention arm after recurrence. Follow-up analyses showing biobehavioral advantages for the Intervention arm contribute to our understanding of how improved survival was achieved.