Phases and classification for Mucositis

The 5-phases of Oral Mucositis Adapted from Sonis:

  • Phase I—Initiation Chemotherapy or radiation-induced reactive oxygen species (ROS) and lipid peroxidation results in DNA damage, release of pathogen-associated molecular pattern (PAMP) and damage-associated molecular pattern molecules (DAMPs) and cellular apoptosis.
  • Phase II—Signaling ROS stimulate the NF-kB pathway, which induces production of proinflammatory cytokines (TNF-α, IL-1β, IL-6).
  • Phase III – Amplification Proinflammatory cytokines trigger tissue injury, apoptosis, vascular permeability, and activation of cyclooxygenase-2.
  • Phase IV—Ulceration Ulceration occurs, which serves as a portal of entry for microorganisms. The presence of bacteria activate macrophages and neutrophils to further produce proinflammatory cytokines.
  • Phase V—Healing Signaling from the submucosa promotes epithelial migration, proliferation and differentiation.


Table I Classification of Oral Mucositis according to the World Health Organization (WHO).

  1. No subjective or objective evidence of mucositis.
  2. Oral pain with or without erythema, without ulceration.
  3. Erythema and ulceration, can swallow solids.
  4. Erythema and ulceration, unable to swallow solids.
  5. Erythema and ulceration, unable to feed.