Common Terminology Criteria for Adverse Events (CTCAE) is widely accepted throughout the oncology community as the standard classification and severity grading scale for adverse events in cancer therapy clinical trials and other oncology settings. Version 5 was published by the NCI Cancer Therapy Evaluation Program (CTEP) in November 2017. It is organized by MedDRA System Organ Class and mapped to MedDRA LLTs with corresponding MedDRA codes, and harmonized with MedDRA at the Adverse Event (AE) level including revised AE terms and severity indicators to reflect clinical effects identified with current oncology interventions.Severity grades are assigned and most are defined to clarify the meaning of the term. CTCAE is designed to integrate into information networks for safety data exchange, and is the primary standard for data management for AE data collection, analysis, and patient outcomes associated with cancer research and care.