Guidelines for Complications of Cancer Treatment Vol VIII Part B

y trauma or tumor, exposing the underlying irradiatedcartilage and making it susceptible to infection andperichondritis resulting in necrosis and laryngeal collapse.Healthy cartilage is avascular and chondroradionecrosis ofthe larynx is largely due to poor vascular and lymphatic flow,caused by endothelial damage and fibrosis. This, whencombined with further insult such as previous or repeatedsurgical intervention and infection, create a demand for tissuerepair, which is beyond the capabilities of the irradiatedcartilage promoting its breakdown.Predisposing factorsFactors affecting the onset of laryngeal chondroradionecrosisare;Radiation dose: Doses >70Gy to the cartilage may increasethe probability of chondroradionecrosis. This may occur dueto inappropriate dose prescription points and/or lack of tissuecompensators leading to a higher dose to the larynx where thetissue separation is minimum.Radiation technique: Modern techniques like IMRT offer theability to control the dose to the larynx to some degree.However careful planning and meticulous planimplementation, treatment delivery and Quality Assurancemeasures are needed to ensure that the laryngeal doses arewithin tolerance.Fractionation schedule: Although there is no direct evidence,it is likely that accelerated fractionation schedules, ifinappropriately delivered, may increase the incidence ofchondroradionecrosis.T Stage: Patients with a large pretreatment tumor and a tumorabutting or involving the thyroid cartilage seem to be at higherrisk for chondroradionecrosis.213