The questionable efficacy of manualized psychological treatments for distressed breast cancer patients: An individual patient data meta-analysis

Previous meta-analyses conclude that psychological treatments are efficacious for emotional distress in breast cancer (BCa). However, the practical relevance of these meta-analyses is questionable; none focused specifically on clinically distressed patients or whether treatment effects were clinically significant. In a two-stage individual patient data (IPD) meta-analysis of 17 randomized controlled trials of manualized psychological treatments in BCa, we evaluated treatment efficacy in distressed BCa patients (n = 1591) using clinical significance and effect size analyses. Outcomes were anxiety, depression, and general distress, evaluated at post-treatment and follow-up. Moderators examined were treatment type, treatment format, therapists’ profession, control condition, age, outcome measure, and trial quality. Treated patients were more likely than controls to recover from anxiety and general distress at post-treatment (14-15% more treated patients recovered), but not at mean 8-months follow-up. Overall recovery rates were low: across outcomes, at post-treatment, only 30-32% of treated patients and 15-25% of controls recovered; at follow-up, only 21-30% of treated patients and 18-35% of controls recovered. Small between-group effect sizes in favour of treatment were found across outcomes at post-treatment (g = 0.32-0.34) but not at follow-up. Across the different analysis methods, few moderator effects were found. More efficacious psychological treatments are needed for distressed BCa patients.