The Association of Loneliness and Social Isolation with Survival in Cancer Patients: A Systematic Review and Meta-Analysis

Background/Objectives: Social isolation and loneliness are distinct but related dimensions of social disconnection that may influence outcomes among individuals with cancer. Previous reviews frequently combined heterogeneous social constructs and often did not distinguish assessments conducted before and after cancer diagnosis. Methods: A systematic review and meta-analysis were conducted following registration in PROSPERO (CRD420261359008). PubMed, Scopus and Web of Science were searched from inception to 2 April 2026. Studies evaluating loneliness and/or social isolation after cancer diagnosis and reporting all-cause or cancer-specific mortality were eligible. Random-effects meta-analyses were performed. Pooled results are reported as hazard ratios (HRs) with 95% confidence intervals (CIs). Results: In total, nine studies involving 20,367 patients with cancer were included. Higher loneliness was associated with increased all-cause mortality (HR = 1.79, 95% CI 1.39–2.31; I2 = 16%). Assessments of social isolation and overall mortality demonstrated a significant association with increased risk of death (HR = 1.36, 95% CI 1.18–1.56; I2 = 22%). A significant association between higher levels of social isolation and cancer-specific mortality (HR = 1.21, 95% CI 1.03–1.42; I2 = 8%) was shown. Sensitivity analyses generally supported the robustness of the findings; however, the association between social isolation and cancer-specific mortality became non-significant after exclusion of the largest contributing cohort. Conclusions: Higher levels of loneliness and social isolation assessed after cancer diagnosis were associated with poorer survival outcomes among patients with cancer. These findings support the importance of considering social disconnection during cancer survivorship and treatment. However, the small number of included studies limits the strengths of conclusions. Further large prospective studies with repeated assessments are needed to clarify these associations and their potential implications for supportive cancer care.