Two of the most commonly used are the World Health Organization (WHO) Oral Toxicity score and the National Cancer Institute Common Toxicity Criteria (NCI-CTC) for Oral Mucositis. While the NCI system has separate scores for appearance (erythema and ulceration) and function (pain and ability to eat solids, liquids, or nothing by mouth), the WHO score combines both elements into a single score that grades the severity of the condition from 0 (no oral mucositis) to 4 (swallowing not possible such that patient needs supplementary nutrition). Another scale developed in 1999, the Oral Mucositis Assessment Scale (OMAS) has been shown to be highly reproducible between observers, responsive over time, and accurate in recording symptoms associated with mucositis. The OMAS provides an objective assessment of oral mucositis based on assessment of the appearance and extent of redness and ulceration in various areas of the mouth.