Biological formation of mucositis is found in five phases: (a) the initiation phase in which chemotherapy acts as a free radical that can damage DNA; (b) The message generation phase in which the activation of transcription factors (NF-kβ) regulates the amount of pro-inflammatory cytokine / interleukin 1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). This evidence concerns the gene IL1B and mucositis.