Clinical Practice Guidelines Adherence and the Impact on Health Outcomes in Oncology: A Systematic Review and Meta‐Analysis

ABSTRACT Aim Clinical practice guidelines (CPGs) are developed to standardize care by providing physicians and decision‐makers with evidence‐based recommendations. This study analyzed the effects of guideline adherence on clinical outcomes in patients with cancer. Methods Five electronic databases were searched through December 2024. Inclusion criteria were randomized control trials (RCT), prospective and retrospective cohort studies on patients with cancer managed with CPG adherent vs. non‐adherent care. Two reviewers screened studies for inclusion, extracted data and assessed the quality of studies. Outcomes of interest included overall survival (OS), disease‐free survival (DFS), and quality of life. A random‐effects model was used to pool the results. Certainty of evidence (CoE) was assessed using the GRADE approach. Results Seventy‐five studies were included. Results suggest that adherence to CPG was associated with improved OS in all disease sites (hazard ratio [HR] = 0.64 (95% confidence interval [CI]: 0.59 to 0.70); p < 0.0001, I 2 : 97%; low CoE). Subgroup analysis by disease site showed similar results except for gynecological cancers where adherence showed no statistically significant improvement in OS (HR = 0.76 (95% CI: 0.53 to 1.08); p = 0.13, I 2 : 77%; low CoE). Further analysis of studies in breast cancer with 5 years follow‐up average showed improvement in OS (HR = 0.70 (95% CI: 0.64 to 0.77); p < 0.001, I 2 : 0%; low CoE). Conclusion Evidence suggests that clinician's adherence to CPG recommendations may improve survival outcomes in patients with cancer. However, the evidence is largely based on retrospective observational studies, highlighting need for prospective trials to further elucidate these associations and better guide clinical practice. Summary What Is Already Known on the Subject What This Study Adds Implications for Practice, Research, and Policy