RESUMEN
Background: The European Society for Medical Oncology (ESMO) guidelines are among the most comprehensive and widely used clinical practice guidelines (CPGs) globally. However, the level of scientific evidence supporting ESMO CPG recommendations has not been systematically investigated. This study assessed ESMO CPG levels of evidence (LOE) and grades of recommendations (GOR), as well as their trends over time across various cancer settings. Methods: We manually extracted every recommendation with the Infectious Diseases Society of America (IDSA) classification from each CPG. We examined the distribution of LOE and GOR in all available ESMO CPG guidelines across different topics and cancer types. Results: Among the 1,823 recommendations in the current CPG, 30% were classified as LOE I, and 43% were classified as GOR A. Overall, there was a slight decrease in LOE I (-2%) and an increase in the proportion of GOR A (+1%) in the current CPG compared to previous versions. The proportion of GOR A recommendations based on higher levels of evidence such as randomized trials (LOE I-II) shows a decrease (71% vs. 63%, p = 0.009) while recommendations based on lower levels of evidence (LOE III-V) show an increase (29% vs. 37%, p = 0.01) between previous and current version. In the current versions, the highest proportion of LOE I (42%) was found in recommendations related to pharmacotherapy, while the highest proportion of GOR A recommendations was found in the areas of pathology (50%) and diagnostic (50%) recommendations. Significant variability in LOE I and GOR A recommendations and their changes over time was observed across different cancer types. Conclusion: One-third of the current ESMO CPG recommendations are supported by the highest level of evidence. More well-designed randomized clinical trials are needed to increase the proportion of LOE I and GOR A recommendations, ultimately leading to improved outcomes for cancer patients.