Effectiveness of Interventions for Reducing Loneliness Among Adult Cancer Survivors: A Systematic Review and Meta-Analysis

Background/Objectives: Loneliness in adult cancer survivors is a frequent and disruptive psychosocial sequela with important consequences for overall health. Psychosocial interventions designed to address this issue are crucial. This systematic review and meta-analysis aimed to examine the efficacy of various psychosocial interventions for reducing loneliness in adult cancer survivors. Methods: A systematic literature search was conducted across PubMed, Web of Science, Scopus, Cochrane Library, PsycINFO, CINAHL Complete and Psicodoc for studies published up to October 2025. Methodological quality was assessed using PRISMA, RoB 2, and the PEDro Scale. The protocol was prospectively registered in PROSPERO (CRD420251174610). Results: Psychosocial interventions showed a significant and moderate effect on reducing loneliness (SMD = 0.46; 95% IC: 0.16 to 0.75). Heterogeneity was high (Q = 30.01; p-value < 0.001; I2 = 70%), and exploratory analyses suggested that differences in loneliness measurement instruments may contribute to this heterogeneity. Additional benefits were observed in anxiety, depression, well-being, and quality of life. Meaning-based and cognitive-behavioral approaches were found to be most effective. A large proportion of the studies showed a high risk of bias. Conclusions: Current evidence suggests that psychosocial interventions may reduce loneliness in adult cancer survivors. However, given the high risk of bias and heterogeneity, findings should be interpreted cautiously. Standardized tools and longitudinal designs remain essential.