Introduction Patients have the right to participate in the shared decision-making on their treatments. There is increasing support for involving cancer patients in the decision-making process for complex treatments, but most previous studies on SDM in cancer patients were focused on children or the elderly. The purpose of this study was to synthesize findings from intervention studies on adults with quantitative outcome measurements.

Methods Three electronic databases (PubMed, CINHAL, and Web of Science) were searched from their inception to June 2023. We included controlled trials on SDM in cancer patients over 18 years of age. Data were extracted using a standardized form. Quality appraisal was based on the Cochrane Risk of Bias Tool.

Results Of the 534 citations retrieved, 8 studies with a total of 2366 participants met the inclusion criteria. Interventions included structured sessions held one to three times per week. SDM methods included weekly assignments, live action videos, and brochures. Treatment preference congruence was higher for intervention groups. Synthesized outcome measurements that reached statistical significance included satisfaction (mean difference in satisfaction questionnaire scores = 0.18; 95% confidence interval [CI]: 0.07, 0.29), decision regret (mean difference in Decision Regret Scale = - 0.27; 95% CI: -0.04, -0.10), and knowledge (mean difference in knowledge scores = 0.23; 95% CI: 0.00, 0.46) after SDM interventions. No adverse events were found among patients.

Discussion This review identified essential components of SDM interventions. Our findings may guide the future design of interventions to support high-quality decision-making by adults with cancer.

Conclusion(s) The development of standard assessment tools for the outcomes of SDM interventions is needed for further research.