Whether psychosocial interventions containing active psychological components prolong survival in cancer patients has been studied for decades, yet findings from primary (RCTs) and secondary research (meta-analyses) remain inconclusive. Our preregistered systematic review, meta-analysis, and multiverse meta-analysis aimed to clarify this research question using contemporary methods of research synthesis. We searched Web of Science, Scopus, MEDLINE, PsycINFO, Embase, and Google Scholar for RCTs of structured psychosocial interventions for cancer patients published until October 17, 2025. We calculated the overall effect; assessed its robustness; estimated a median survival benefit, characterized the psychological components included in the interventions; examined risk of bias, study quality, meta-analytic post hoc power, and sponsorship bias; explored 25 substantive and methodological moderators; and considered publication bias as well as p-hacking. Using multiverse meta-analysis, we calculated multiple overall effects based on reasonable specifications employed in prior meta-analyses (descriptive analysis) and compared them with the 95% CI band of 1000 simulated overall effects assuming no true effect (inferential analysis). Psychosocial interventions, provided alongside medical treatment, demonstrated a small, positive and robust overall effect on survival in cancer patients, with an HR of 0.80, 95% CI 0.71, 0.90 across 32 RCTs comprising 5704 participants. Heterogeneity was moderate to substantial with an I² = 48% and a wide 95% PI (HR 0.49-1.29). Median survival time benefit was estimated at 3.9 months, 95% CI - 0.7, 8.5, based on data from 16 trials. The psychological components most frequently applied were educational, cognitive-behavioral, emotionally expressive, and group-based social support. Low average meta-analytic post hoc power (17%) likely contributed to inconsistent findings among trials. Multiverse meta-analysis confirmed the presence of a general overall survival effect and indicated that previously conflicting meta-analytic conclusions primarily stemmed from differences in effect size metrics and analytic decisions. Psychosocial (psychological) interventions appear to improve survival in cancer patients, with effect sizes comparable in magnitude to effects previously reported in the literature for medical cancer treatments such as chemo-, radio-, and hormone therapy. The certainty of evidence was rated moderate, primarily due to statistical heterogeneity, hence effects might not generalize equally to all populations. Considering survival impact, established psychological benefits, favorable safety profile, and comparatively low cost, the findings support a paradigm shift toward establishing psychosocial interventions alongside medical therapy as a standard component of comprehensive cancer care; potentially guiding future research and clinical practice.
Asakawa-Haas et al. (Wed,) studied this question.