A Chinese prospective observational trial of 63 patients receiving IMRT for head and neck cancer demonstrates higher radiation dose to the olfactory region was associated with worse smell function over time. The olfactory fossae are pretty easy to contour (see supplement for illustration). A mean olfactory dose >22 Gy emerged as a critical inflection point, conferring a 20-fold increased odds of olfactory dysfunction, with some patients experiencing persistent deficits up to 1 year. These findings highlight olfactory structures as a dose-sensitive organ at risk and support incorporating dose constraints to preserve long-term quality of life. | Chang, JAMA Netw Open 2025
