Single-center clinical trial of intensity-modulated radiotherapy and smell function in head and neck cancer

A substantial proportion of patients with head and neck cancer (HNC) experience smell dysfunction during or after radiotherapy. A non randomized clinical trial at Chang Gung Memorial Hospital (Taiwan) evaluated association of intensity-modulated radiotherapy (IMRT) with olfactory function in patients with HNC. Patients scheduled for IMRT underwent olfactory function assessment using the Taiwan Smell Identification Test before IMRT, after IMRT, and at 1, 3, 6, and 12 months after treatment. Nasal endoscopy was used to rule out confoundig nasal conditions. Among 63 patients with a normal pretreatment sense of smell, higher radiation doses to the olfactory region were associated with moderate smell dysfunction. An inflection point dose of 22 Gy was identified; doses above this point increased the odds of dysfunction by 20-fold (OR 20.65; 95% CI 2.60-164.35), and some patients had lasting impairment for up to 1 year. The authors conclude that limiting radiation exposure may reduce the risk of smell dysfuntion in patients with HNC.