New thoughts on the initiation of mucositis.

It has been slightly more than a decade since the classic mechanistic paradigm that defined the pathogenesis of mucositis was revised. A five-stage sequence of linked biological events forms the basis for our current understanding of how regimen-related mucosal injury occurs. The first stage is the initiation phase, although the gateway to toxicity has been the least studied. This essay proposes new thoughts on the phase's components, how they might interact, and how they present new opportunities for treatment interventions and mucositis risk prediction.