RESUMO
BACKGROUND: The Spanish Society of Medical Oncology (SEOM) has provided open-access guidelines for cancer since 2014. However, no independent assessment of their quality has been conducted to date. This study aimed to critically evaluate the quality of SEOM guidelines on cancer treatment. METHODS: Appraisal of Guidelines for Research and Evaluation II (AGREE II) and AGREE-REX tool was used to evaluate the qualities of the guidelines. RESULTS: We assessed 33 guidelines, with 84.8% rated as "high quality". The highest median standardized scores (96.3) were observed in the domain "clarity of presentation", whereas "applicability" was distinctively low (31.4), with only one guideline scoring above 60%. SEOM guidelines did not include the views and preferences of the target population, nor did specify updating methods. CONCLUSIONS: Although developed with acceptable methodological rigor, SEOM guidelines could be improved in the future, particularly in terms of clinical applicability and patient perspectives.