Global use of traditional, complementary and integrative medicine among adults with cancer in hospital and clinical settings: A systematic review and meta-analysis

Introduction Traditional, Complementary and Integrative Medicine (TCIM) use is common among adults with cancer worldwide, yet global prevalence estimates remain outdated and fragmented. This meta-analysis aimed to provide an updated estimate of TCIM use among adults with cancer in hospital or clinical settings and to explore variations by region, income level, cancer type, and sex. Methods PubMed, Embase, Web of Science, CINAHL, and Google Scholar were systematically searched from January 2000 to February 2024. Eligible studies were cross-sectional and included adults with cancer assessed in clinical or hospital settings, and reported quantitative data on TCIM use. Prevalence estimates were logit-transformed and pooled using a random-effects model with maximum likelihood estimation and Hartung–Knapp adjustment. Heterogeneity was assessed using I², and subgroup analyses and meta-regression were performed to explore sources of variability. Certainty of evidence was evaluated using a pragmatic adaptation of GRADE. Results Forty-five studies including 24,721 patients from 28 countries met inclusion criteria. The pooled prevalence of TCIM use among adults with cancer in hospital or clinical settings was 51% (95% CI: 45–56%). TCIM use was highest in the Americas (64%) and lowest in Europe (45%). Biologically based practices were the most commonly reported modalities. Heterogeneity was high (I² = 98%), with prevalence estimates ranging from 18% to 91% across studies, indicating substantial inconsistency, and small-study effects were suspected. The certainty of evidence was rated as low. Conclusions TCIM use in hospital or clinical settings remains highly prevalent among adults with cancer receiving clinical care, underscoring the need for systematic screening, patient–clinician dialogue, and evidence-informed integration of safe TCIM practices into supportive oncology care. Future research should prioritize standardized definitions, improved methodological harmonization, and individual participant data meta-analyses to reduce heterogeneity.