Table 1.

Grading criteria.

Grade	1	2	3	4
RTOG	Erythema	Patchy reaction (<1.5 cm, non-contiguous)	Confluent mucositis (>1.5 cm, contiguous)	Ulceration, necrosis, bleeding
WHO	Sore throat ± erythema, able to eat solid food	Ulcers ± erythema, able to eat solid food	Ulcers with extensive erythema, requires liquid diet	alimentation not possible
CTCAE v5.0	Asymptomatic or mild symptoms; intervention not indicated	Moderate pain; not interfering with oral intake; modified diet indicated	Severe pain; interfering with oral intake	Life-threatening consequences; urgent intervention indicated
NCI-CTC	Erythema of the mucosa	Patchy pseudomembranous reaction (patches generally ≤1.5 cm in diameter and non-contiguous)	Confluent pseudomembranous reaction (contiguous patches generally >1.5 cm in diameter)	Necrosis or deep ulceration; may include bleeding not induced by minor trauma or abrasion
WCCNR	Lesions: none Color: pink Bleeding: none	Lesions: 1–4 Color: slight red Bleeding: none	Lesions: more than 4 Color: moderately red Bleeding: with eating and hygiene	Lesions: coalescing Color: very red Bleeding: spontaneous

RTOG, Radiation Therapy Oncology Group; WHO, World Health Organization; CTCAE, Common Terminology Criteria for Adverse Events; NCI-CTC, National Cancer institute Common Toxicity Criteria; WCCNR, Western Consortium for Cancer Nursing Research.