Truce: Outcomes and mechanisms of change of a seven-week acceptance and commitment therapy programs for young people whose parent has cancer.

Truce is an Acceptance and Commitment Therapy group program for young people who have a parent with cancer. In a pragmatic controlled trial, we compared Truce with a wait-list condition to assess its effect on unmet needs and distress. We also investigated how process variables—mindfulness, cognitive inflexibility, family functioning, and life events—might influence outcomes. Participants' unmet needs improved over time (β^ = −5.01, SE = 16.48, p = 0.036, effect size = 0.42), and those improvements were greater for the intervention group compared to controls (β^ = −5.03, SE = 2.41, p = 0.040, effect size = 0.29). There was no evidence of a significant program benefit for distress. For the intervention group, greater improvements in unmet needs were associated with higher baseline distress (t = 2.36, df = 47, p = 0.022), and being less mindful at baseline (t = 2.07, df = 47, p = 0.044). No significant mediators were identified. For the control group only, experiencing negative/mixed life events related to cancer was a significant moderator of improvement (t = −2.36, df = 33, p = 0.024). Truce appears to offer therapeutic benefits to young people who have a parent with cancer, over and above the expected adjustment to the situation over time. The program seems to buffer the impact of negative cancer-related life events on participants’ well-being, but the mechanisms of change remain unclear.