The incidence of LENT is related to both total radiation exposure and the length of time a patient is out from completing radiotherapy. The higher the dose, the longer the interval from exposure, the greater the risk. In many cases, resulting radionecrotic lesions seriously impair form and function, and require extensive surgical correction or repair. Such surgery is fraught with complications, hence the inclusion of a "prophylactic" hyperbaric oxygen arm. A disturbing degree of mortality further complicates the development of LENT.