Clinical practice guidelines serve as a guide for doctors and outline appropriate methods of treatment and care. Guidelines can address specific clinical situations (disease-oriented) or use of approved medical products, procedures, or tests (modality-oriented). Using the best available evidence, ASCO expert panels identify and develop practice recommendations for specific areas of cancer care that would benefit from the availability of practice guidelines. Topics for guidelines are selected on the basis of significant clinical or economic importance; presence of variations in patterns of, or access to, care; availability of suitable data; and ethical considerations.